Introduction to Chemistry
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Questions and Answers

What is chemistry mainly concerned with?

  • Studying the behavior of matter (correct)
  • Understanding the universe
  • Describing physical phenomena
  • Classifying materials

    • What is meant by the term 'matter' in chemistry?

  • Only liquids and gases
  • Only the physical world around us
  • All substances and materials in the universe (correct)
  • Only solid substances

    • What are the two main aspects of chemistry?

  • Classifying and naming compounds
  • Understanding changes and existence of materials (correct)
  • Measuring and weighing substances
  • Describing and analyzing materials

    • What is a key characteristic of matter?

    <p>Has mass</p> Signup and view all the answers

    Why is the small-sized brick lighter than the big-sized brick?

    <p>It contains less matter</p> Signup and view all the answers

    What happens when two trucks try to cross each other in a narrow lane?

    <p>They will collide</p> Signup and view all the answers

    What is the property of matter that causes it to remain at rest or in motion?

    <p>Inertia</p> Signup and view all the answers

    What will happen to a football placed in the center of a playground?

    <p>It will remain there unless disturbed by an external force</p> Signup and view all the answers

    What is the main difference between mass and weight?

    <p>Mass is the amount of matter, while weight is the force of gravity</p> Signup and view all the answers

    Why do two stools cannot occupy the same space at the same time?

    <p>Because matter occupies space</p> Signup and view all the answers

    What is the primary focus of chemistry?

    <p>The behavior and properties of matter</p> Signup and view all the answers

    What is a fundamental characteristic of all matter?

    <p>It has mass</p> Signup and view all the answers

    What happens when an external force is applied to an object at rest?

    <p>It is disturbed from its position</p> Signup and view all the answers

    Why do two objects of different sizes occupy different amounts of space?

    <p>The smaller object has less mass</p> Signup and view all the answers

    What is the term for the amount of matter in an object?

    <p>Mass</p> Signup and view all the answers

    What is the property of matter that causes it to resist changes in motion?

    <p>Inertia</p> Signup and view all the answers

    How do we know that air is matter?

    <p>Because it has mass</p> Signup and view all the answers

    What is the result of two objects trying to occupy the same space?

    <p>They collide</p> Signup and view all the answers

    What is the primary way that matter behaves?

    <p>It maintains its state of motion</p> Signup and view all the answers

    What is the relationship between the amount of matter in an object and its mass?

    <p>The amount of matter determines the mass</p> Signup and view all the answers

    What is the force that pulls objects towards the Earth's surface?

    <p>Gravity</p> Signup and view all the answers

    According to the law of conservation of mass, what remains the same during physical and chemical changes?

    <p>Total mass of the matter</p> Signup and view all the answers

    What is the characteristic of matter that determines its physical behavior?

    <p>Movement or motion</p> Signup and view all the answers

    What is the evidence that supports the kinetic theory of matter?

    <p>The movement of pollen grains in water</p> Signup and view all the answers

    What is not considered as matter?

    <p>Heat or light</p> Signup and view all the answers

    What is the origin of the word 'kinetic'?

    <p>Greek word 'Kinos' meaning to move</p> Signup and view all the answers

    Why do fruits always fall downwards from the trees?

    <p>Because of the force of attraction exerted by the Earth</p> Signup and view all the answers

    What is the result of heating tin metal in a flask?

    <p>It is converted into tin oxide</p> Signup and view all the answers

    Why do solids, liquids, and gases have different properties?

    <p>Because of their different movements</p> Signup and view all the answers

    What is the characteristic of matter that makes it impossible to be destroyed?

    <p>It cannot be destroyed or created</p> Signup and view all the answers

    What is the force that attracts objects towards the Earth's surface?

    <p>Gravity</p> Signup and view all the answers

    What is the term for the amount of matter in an object?

    <p>Mass</p> Signup and view all the answers

    What is the characteristic of matter that determines its physical behavior?

    <p>Motion</p> Signup and view all the answers

    What is the result of heating tin metal in a flask?

    <p>Its weight remains unchanged</p> Signup and view all the answers

    What is the origin of the word 'kinetic'?

    <p>From the Greek word 'Kinos' meaning to move</p> Signup and view all the answers

    What is the evidence that supports the kinetic theory of matter?

    <p>Movement of pollen grains in water</p> Signup and view all the answers

    What is not considered as matter?

    <p>All of the above</p> Signup and view all the answers

    What is the law that states that matter cannot be created or destroyed?

    <p>Law of Conservation of Mass</p> Signup and view all the answers

    What is the reason why fruits always fall downwards from the trees?

    <p>Gravity</p> Signup and view all the answers

    What is the characteristic of particles of matter that determines their physical properties?

    <p>Motion</p> Signup and view all the answers

    What is the term for the zig-zag movement of small particles suspended in a liquid or gas?

    <p>Brownian motion</p> Signup and view all the answers

    What is the result of an increase in kinetic energy of particles of matter?

    <p>All of the above</p> Signup and view all the answers

    What is the main conclusion that can be drawn from the existence of Brownian motion?

    <p>Matter is made up of tiny particles</p> Signup and view all the answers

    What is the term for the theory that describes matter as consisting of atoms, molecules, or ions in constant motion?

    <p>Kinetic theory of matter</p> Signup and view all the answers

    What is a characteristic of particles of matter in a solid state?

    <p>They vibrate about their average position</p> Signup and view all the answers

    What is the force that exists between particles of matter in a liquid state?

    <p>Intermolecular force</p> Signup and view all the answers

    What is the result of particles being in a state of random continuous motion?

    <p>They gain kinetic energy</p> Signup and view all the answers

    What is the characteristic of particles of matter that determines their physical behavior?

    <p>Motion</p> Signup and view all the answers

    What is the main postulate of the kinetic theory of matter?

    <p>Matter consists of molecules</p> Signup and view all the answers

    What is the direction of motion of particles in a gas?

    <p>Random and zig-zag</p> Signup and view all the answers

    What is the outcome of the collisions between particles in a given substance?

    <p>The total energy of the particles remains the same.</p> Signup and view all the answers

    What is the force that causes the movement of particles in a given substance?

    <p>Intermolecular force</p> Signup and view all the answers

    What would happen to the particles if they did not collide elastically?

    <p>They would come to rest.</p> Signup and view all the answers

    What is the purpose of the starch iodide paper in the experiment?

    <p>To detect the presence of iodine particles.</p> Signup and view all the answers

    What does the diffusion of iodine particles indicate?

    <p>The particles are mobile.</p> Signup and view all the answers

    What is the observation that suggests the particles are mobile?

    <p>The starch iodide paper turns blue when brought near the test tube.</p> Signup and view all the answers

    What is the significance of the intermolecular spaces in a given substance?

    <p>It determines the magnitude of the intermolecular force.</p> Signup and view all the answers

    What is the result of the experiment with the iodine and starch iodide paper?

    <p>The particles are found to be mobile.</p> Signup and view all the answers

    What is the characteristic of the collisions between particles in a given substance?

    <p>They are elastic.</p> Signup and view all the answers

    What is the conclusion that can be drawn from the experiment with the iodine and starch iodide paper?

    <p>Particles of matter are always mobile.</p> Signup and view all the answers

    What is observed when a starch iodide paper is brought near the mouth of the test tube containing iodine?

    <p>The starch iodide paper becomes blue.</p> Signup and view all the answers

    Why do salts get dissolved in water easily even when not externally stirred?

    <p>Due to the kinetic molecular theory of matter.</p> Signup and view all the answers

    What determines the physical behavior of particles of matter in different states?

    <p>All of the above.</p> Signup and view all the answers

    What is the characteristic of particles in a solid state?

    <p>They are closely packed and have fixed positions.</p> Signup and view all the answers

    Why do solids have a definite shape and volume?

    <p>Due to their strong intermolecular forces.</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state?

    <p>They are able to move past each other freely.</p> Signup and view all the answers

    Why do solids have high density?

    <p>Due to their closely packed particles.</p> Signup and view all the answers

    What is the characteristic of particles in a gas state?

    <p>They are able to move freely and have high energy.</p> Signup and view all the answers

    What is the result of the diffusion of iodine particles in the test tube?

    <p>The iodine particles spread throughout the test tube.</p> Signup and view all the answers

    What is the evidence that supports the kinetic theory of matter?

    <p>The experiment with iodine particles in a test tube.</p> Signup and view all the answers

    What is the main reason why salt dissolves easily in water?

    <p>Because of the kinetic energy of water molecules</p> Signup and view all the answers

    What is the characteristic of particles in a solid state?

    <p>They are closely packed and have fixed positions</p> Signup and view all the answers

    What happens to the iodine particles in the experiment with the starch iodide paper?

    <p>They spread throughout the test tube</p> Signup and view all the answers

    What is the main difference between the three states of matter?

    <p>All of the above</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state?

    <p>They are widely spaced and have random motion</p> Signup and view all the answers

    What is the result of an increase in kinetic energy of particles of matter?

    <p>They move faster and spread out</p> Signup and view all the answers

    What is the characteristic of particles of matter that determines their physical behavior?

    <p>All of the above</p> Signup and view all the answers

    What is the main postulate of the kinetic theory of matter?

    <p>Matter is made up of atoms, molecules, or ions in constant motion</p> Signup and view all the answers

    What is the result of particles being in a state of random continuous motion?

    <p>They diffuse and spread out</p> Signup and view all the answers

    What is the characteristic of particles in a gas state?

    <p>They are widely spaced and have random motion</p> Signup and view all the answers

    What is a characteristic of particles in a liquid state?

    <p>They are loosely packed and their positions are not fixed</p> Signup and view all the answers

    What is the primary difference between a liquid and a gas?

    <p>Liquids have a definite volume, while gases do not</p> Signup and view all the answers

    What is the reason why liquids cannot be compressed?

    <p>Their particles are loosely packed and have freedom of motion</p> Signup and view all the answers

    What is the characteristic of particles in a gas state?

    <p>They are wide apart and their positions are not fixed</p> Signup and view all the answers

    What is the primary difference between the density of a liquid and a gas?

    <p>Liquids have a higher density, while gases have a lower density</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state that allows them to flow?

    <p>They are loosely packed and their positions are not fixed</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state?

    <p>Particles are loosely packed and their positions are not fixed</p> Signup and view all the answers

    What is the main difference between the energy associated with particles in a liquid and a gas?

    <p>Particles in a liquid have considerable energy, while in a gas they have maximum energy</p> Signup and view all the answers

    What is the characteristic of a liquid in terms of its shape and volume?

    <p>A liquid has a definite volume but no definite shape</p> Signup and view all the answers

    What is the characteristic of particles in a gas?

    <p>Particles are wide apart and their positions are not fixed</p> Signup and view all the answers

    What is the characteristic of a gas in terms of its compressibility?

    <p>A gas can be compressed and is not rigid</p> Signup and view all the answers

    What is the characteristic of a liquid in terms of its density?

    <p>A liquid has a relatively high density</p> Signup and view all the answers

    What is the reason why a wooden block is considered a solid?

    <p>It has a fixed shape and is rigid</p> Signup and view all the answers

    Why is a rubber band considered a solid?

    <p>It regains its shape when the force is removed</p> Signup and view all the answers

    What is a characteristic of molecules in a solid?

    <p>They have a strong force of attraction between them</p> Signup and view all the answers

    What is a characteristic of molecules in a liquid?

    <p>They lie far apart from each other</p> Signup and view all the answers

    What happens to the shape of a rubber band when a force is applied?

    <p>It undergoes a change in shape</p> Signup and view all the answers

    What is a characteristic of molecules in a solid state?

    <p>They have a fixed position</p> Signup and view all the answers

    What is the reason why a rubber band is considered a solid, despite undergoing a change in shape?

    <p>It regains its shape when the force is removed</p> Signup and view all the answers

    What is a characteristic of the kinetic model of a solid?

    <p>Molecules have a fixed position</p> Signup and view all the answers

    What is the primary reason why a rubber band is considered a solid?

    <p>It regains its original shape when the force is removed</p> Signup and view all the answers

    What is a characteristic of the molecules in a solid?

    <p>They are closely packed</p> Signup and view all the answers

    What is the main difference between the molecules in a solid and a liquid?

    <p>The molecules in a liquid are farther apart than those in a solid</p> Signup and view all the answers

    Why is a wooden block considered a solid?

    <p>It has a fixed shape and is rigid</p> Signup and view all the answers

    What is the characteristic of the molecules in a liquid that allows them to move freely?

    <p>The intermolecular force of attraction between the molecules is not strong enough to keep them bonded to one position</p> Signup and view all the answers

    What is the main characteristic of a solid?

    <p>It has a fixed shape and is rigid</p> Signup and view all the answers

    What is the arrangement of molecules in a solid?

    <p>They are arranged in a definite manner</p> Signup and view all the answers

    What is the primary reason why a solid maintains its shape?

    <p>The molecules are fixed in position</p> Signup and view all the answers

    What is the force that resists the relative motion of layers in a flowing liquid?

    <p>Frictional force</p> Signup and view all the answers

    Why does glycerine have a higher viscosity than water or alcohol?

    <p>Because of its stronger intermolecular forces</p> Signup and view all the answers

    What happens to the viscosity of a liquid when its temperature increases?

    <p>It decreases</p> Signup and view all the answers

    What is the term for the internal friction or resistance in a flowing liquid?

    <p>Viscosity</p> Signup and view all the answers

    Which of the following liquids is more viscous?

    <p>Honey</p> Signup and view all the answers

    What is the result of the relative motion between layers in a flowing liquid?

    <p>Increased friction</p> Signup and view all the answers

    What is the force responsible for the stationary layer of liquid near a plate?

    <p>Friction</p> Signup and view all the answers

    What is the relationship between intermolecular forces and viscosity?

    <p>Stronger intermolecular forces lead to higher viscosity</p> Signup and view all the answers

    What is the effect of increasing temperature on the intermolecular forces in a liquid?

    <p>It decreases the intermolecular forces</p> Signup and view all the answers

    What is the term for the resistance to flow in a liquid caused by molecular forces?

    <p>Viscosity</p> Signup and view all the answers

    What is the reason for the surface tension of a liquid?

    <p>The intermolecular forces between surface molecules are unbalanced</p> Signup and view all the answers

    What happens to the surface tension of a liquid when the temperature is increased?

    <p>It decreases</p> Signup and view all the answers

    What is the relationship between surface tension and intermolecular attractive forces?

    <p>Surface tension is directly proportional to intermolecular forces</p> Signup and view all the answers

    What is the characteristic of the layer of liquid in contact with the wall of a tube?

    <p>It is stationary</p> Signup and view all the answers

    What is the term for the property of a liquid that resists flow?

    <p>Viscosity</p> Signup and view all the answers

    What is the velocity profile of a liquid flowing through a tube?

    <p>Highest in the centre and lowest at the wall</p> Signup and view all the answers

    What is the effect of temperature on intermolecular forces in a liquid?

    <p>It decreases them</p> Signup and view all the answers

    What is the reason for the difference in velocity between the centre and the wall of a tube?

    <p>Friction between the liquid and the wall</p> Signup and view all the answers

    What is the characteristic of a liquid with high surface tension?

    <p>It has strong intermolecular forces</p> Signup and view all the answers

    What is the effect of surface tension on the Cleaning ability of a liquid?

    <p>It increases the cleaning ability</p> Signup and view all the answers

    What is the reason for the surface tension of a liquid?

    <p>Because of the attractive forces between molecules</p> Signup and view all the answers

    What happens to the surface tension of a liquid when the temperature increases?

    <p>It decreases</p> Signup and view all the answers

    What is the property of a liquid that is responsible for its ability to flow through a tube?

    <p>Viscosity</p> Signup and view all the answers

    Why do the molecules at the surface of a liquid experience an unbalanced force?

    <p>Because of the attractive forces from molecules below</p> Signup and view all the answers

    What is the result of the unbalanced force at the surface of a liquid?

    <p>The surface molecules experience a net downward force</p> Signup and view all the answers

    What is the effect of temperature on the intermolecular forces between molecules of a liquid?

    <p>Intermolecular forces decrease with temperature</p> Signup and view all the answers

    What is the relationship between the magnitude of surface tension and intermolecular attractive forces?

    <p>The magnitude of surface tension is directly proportional to the intermolecular attractive forces</p> Signup and view all the answers

    What is the property of a liquid that determines its ability to resist changes in shape?

    <p>Surface tension</p> Signup and view all the answers

    What is the direction of motion of the layer of liquid in contact with the wall of a tube?

    <p>Stationary</p> Signup and view all the answers

    What is the velocity of the liquid in the centre of a tube?

    <p>Highest</p> Signup and view all the answers

    What is the internal friction or resistance that resists the relative motion of a liquid?

    <p>Viscosity</p> Signup and view all the answers

    Why does glycerine have more viscosity than water or alcohol?

    <p>Due to stronger intermolecular forces</p> Signup and view all the answers

    What happens to the viscosity of a liquid when the temperature is increased?

    <p>It decreases</p> Signup and view all the answers

    What is the reason for the stationary layer in contact with the glass plate in a liquid flowing over it?

    <p>Due to adhesion</p> Signup and view all the answers

    What is the characteristics of a liquid with high viscosity?

    <p>It flows with difficulty</p> Signup and view all the answers

    What is the relation between intermolecular forces and viscosity?

    <p>Strong intermolecular forces lead to high viscosity</p> Signup and view all the answers

    What is the result of the relative motion between different layers of a liquid?

    <p>Each layer exerts a drag on the next</p> Signup and view all the answers

    What is the reason for the continuous increase in velocity of different layers of a liquid flowing over a glass plate?

    <p>Due to relative motion</p> Signup and view all the answers

    What is the characteristic of honey that makes it more viscous than water?

    <p>Stronger intermolecular forces</p> Signup and view all the answers

    What is the result of the work done to maintain the flow of a liquid?

    <p>It maintains the flow of the liquid</p> Signup and view all the answers

    What is the primary reason for the surface tension of a liquid?

    <p>Intermolecular attractive forces</p> Signup and view all the answers

    What happens to the surface tension of a liquid when its temperature is increased?

    <p>It decreases</p> Signup and view all the answers

    What is the relationship between surface tension and the nature of a liquid?

    <p>Surface tension is a measure of intermolecular attractive forces</p> Signup and view all the answers

    What is the characteristic of liquid flow through a tube?

    <p>The layer in contact with the tube is stationary</p> Signup and view all the answers

    What is the property of a liquid that causes it to resist changes in shape?

    <p>Viscosity</p> Signup and view all the answers

    What is the effect of increasing temperature on the viscosity of a liquid?

    <p>It decreases the viscosity</p> Signup and view all the answers

    What is the relationship between the velocity of liquid layers in a tube?

    <p>The velocity of the layers decreases from the center to the wall</p> Signup and view all the answers

    What is the force responsible for the surface tension of a liquid?

    <p>Intermolecular attractive force</p> Signup and view all the answers

    What is the result of the imbalance of forces at the surface of a liquid?

    <p>The liquid surface is under tension</p> Signup and view all the answers

    Why do clothes get washed more efficiently in hot water?

    <p>Because of decreased surface tension</p> Signup and view all the answers

    What is the reason for the internal resistance or viscosity in a liquid?

    <p>Molecular force working between the molecules of the liquid</p> Signup and view all the answers

    What happens to the velocity of different layers of a liquid flowing over a glass plate?

    <p>The velocity of different layers increases continuously with the distance from the fixed surface</p> Signup and view all the answers

    Why does glycerine have more viscosity than water or alcohol?

    <p>Glycerine has a higher intermolecular force</p> Signup and view all the answers

    What is the effect of temperature on the viscosity of a liquid?

    <p>Viscosity decreases with an increase in temperature</p> Signup and view all the answers

    What is the reason for the difference in viscosity between honey and water?

    <p>Honey has a stronger intermolecular force</p> Signup and view all the answers

    What is the role of each layer in a liquid flowing through a pipe?

    <p>Each layer exerts a drag on the next layer</p> Signup and view all the answers

    What is the characteristic of a liquid with high viscosity?

    <p>It flows slowly and with difficulty</p> Signup and view all the answers

    What is the relationship between intermolecular forces and viscosity?

    <p>High intermolecular forces result in high viscosity</p> Signup and view all the answers

    What is the reason for the difference in flow of glycerine and water?

    <p>Glycerine has a higher intermolecular force</p> Signup and view all the answers

    What is the characteristic of a liquid with low viscosity?

    <p>It flows easily and quickly</p> Signup and view all the answers

    What is the state of matter of bromine at a temperature greater than -7.2°C but less than 59°C?

    <p>Liquid</p> Signup and view all the answers

    What is the primary reason why gases exert pressure?

    <p>Due to constant collision and bombardment on the walls of the vessel</p> Signup and view all the answers

    What is true about the composition of gases?

    <p>They have similar composition in all parts</p> Signup and view all the answers

    What is the result of applying pressure and cooling to a gas?

    <p>It becomes a liquid</p> Signup and view all the answers

    What is the reason why gases fill the entire space of their container?

    <p>Due to high kinetic energy and low intermolecular forces</p> Signup and view all the answers

    What is the direction of pressure exerted by a gas?

    <p>In all directions</p> Signup and view all the answers

    What is the term for the movement of particles in a gas?

    <p>Diffusion</p> Signup and view all the answers

    What is true about the molecules of a gas?

    <p>They have high kinetic energy and large intermolecular spaces</p> Signup and view all the answers

    What happens when the kinetic energy of particles of matter increases?

    <p>They move randomly</p> Signup and view all the answers

    What is the term for the theory that describes matter as consisting of atoms, molecules, or ions in constant motion?

    <p>Kinetic theory of matter</p> Signup and view all the answers

    What is the term for the force that exists between particles of matter in a liquid state?

    <p>Intermolecular forces</p> Signup and view all the answers

    What is the state of matter of bromine at a temperature greater than -7.2°C but less than 59°C?

    <p>Liquid</p> Signup and view all the answers

    What is the main reason why gases exert pressure in all directions?

    <p>Due to the constant collision of molecules with the container walls</p> Signup and view all the answers

    What is the characteristic of gases that allows them to fill completely the vessel they are contained in?

    <p>Large intermolecular spaces and high kinetic energy</p> Signup and view all the answers

    What is the process by which gases can be converted into liquids?

    <p>Liquefaction</p> Signup and view all the answers

    What is the characteristic of gases that makes them homogeneous in nature?

    <p>Similar composition in all parts</p> Signup and view all the answers

    What is the result of the constant collision of gas molecules with the container walls?

    <p>The gas exerts pressure on the container walls</p> Signup and view all the answers

    What is the primary difference between the movement of gas molecules and liquid molecules?

    <p>Gas molecules move faster than liquid molecules</p> Signup and view all the answers

    What is the characteristic of a liquid that allows it to take the shape of its container?

    <p>Definite volume and no definite shape</p> Signup and view all the answers

    What is the result of the high kinetic energy of gas molecules?

    <p>The gas molecules spread out and fill the container</p> Signup and view all the answers

    What is the characteristic of gases that allows them to exert pressure in all directions?

    <p>Negligible force of attraction between molecules</p> Signup and view all the answers

    What is the term for the process by which gases intermix with one another without any mechanical aid?

    <p>Diffusion</p> Signup and view all the answers

    What is the main application of Graham's law of diffusion?

    <p>All of the above</p> Signup and view all the answers

    What are the three states of matter that are interconvertible?

    <p>Solid, liquid, and gas</p> Signup and view all the answers

    What is the change in condition necessary for the interconversion of states of matter?

    <p>All of the above</p> Signup and view all the answers

    What happens when a bottle of ammonia is opened in a laboratory?

    <p>Its pungent smell can be experienced all over the laboratory</p> Signup and view all the answers

    What is the result of heating ice above 0°C?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What happens when a candle is lit up?

    <p>The wax melts and rises up the wick</p> Signup and view all the answers

    What is the process by which gases are separated from a mixture?

    <p>Diffusion</p> Signup and view all the answers

    What is the result of further heating a liquid above 100°C?

    <p>It changes into a gaseous state</p> Signup and view all the answers

    What is the characteristic of gases that allows them to intermix with one another?

    <p>They are able to form a homogeneous mixture</p> Signup and view all the answers

    What is the process of converting gases into liquid state?

    <p>By increasing the pressure of the gas</p> Signup and view all the answers

    Why does the temperature of the system not change after the melting point is achieved?

    <p>Because the heat is used to change the state of the substance</p> Signup and view all the answers

    What is the term for the energy required to change a solid into a liquid?

    <p>Latent heat</p> Signup and view all the answers

    What happens when a substance changes its state?

    <p>It can be reverted to its original state by altering its temperature or pressure</p> Signup and view all the answers

    Why can sugar not be converted from solid to liquid?

    <p>Because it decomposes when heated</p> Signup and view all the answers

    What happens when the temperature of a substance is changed?

    <p>Its physical state changes</p> Signup and view all the answers

    What is the term for the change of state of a substance?

    <p>Phase transition</p> Signup and view all the answers

    Why is latent heat called 'hidden heat'?

    <p>Because it is hidden in the system</p> Signup and view all the answers

    What is the result of increasing the pressure of a gas?

    <p>The gas becomes a liquid</p> Signup and view all the answers

    What is the relationship between the temperature and physical state of a substance?

    <p>Temperature determines the physical state</p> Signup and view all the answers

    What is the property that allows ammonia to spread its smell all over the laboratory?

    <p>Diffusion</p> Signup and view all the answers

    According to Graham's law of diffusion, what can be determined?

    <p>Relative densities and molecular weights of gases</p> Signup and view all the answers

    What is the process of changing a mixture of gases into individual gases?

    <p>Separation</p> Signup and view all the answers

    What are the three main states of matter?

    <p>Solid, Liquid, Gas</p> Signup and view all the answers

    What is the term for the process of changing from one state of matter to another?

    <p>Interconversion</p> Signup and view all the answers

    What is the result of heating ice?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What is the result of heating water above 100°C?

    <p>It changes into a gas state</p> Signup and view all the answers

    What happens when a candle is lit?

    <p>The wax changes into a liquid state</p> Signup and view all the answers

    What is the process by which particles intermix and spread out?

    <p>Diffusion</p> Signup and view all the answers

    What is the result of decreasing the pressure of a gas?

    <p>It remains in a gas state</p> Signup and view all the answers

    What is necessary to convert gases such as nitrogen, oxygen, hydrogen, and helium into a liquid state?

    <p>Cooling and increasing the pressure of the gas</p> Signup and view all the answers

    Why does the temperature of a system not change after the melting point is achieved until all the ice melts?

    <p>The heat supplied is used to change the state by breaking the intermolecular forces of attraction</p> Signup and view all the answers

    What is the energy required to change a solid into a liquid called?

    <p>Latent heat</p> Signup and view all the answers

    What happens when a substance changes its state?

    <p>It can be reverted to the original state by altering its temperature or pressure</p> Signup and view all the answers

    Why can't sugar be changed from a solid to a liquid state?

    <p>Because sugar decomposes when heated</p> Signup and view all the answers

    What is the term for the temperature at which a substance changes from a solid to a liquid state?

    <p>Melting point</p> Signup and view all the answers

    What happens when a substance is heated and changes its physical state?

    <p>Its physical properties change</p> Signup and view all the answers

    What is the result of changing the pressure of a gas?

    <p>The gas changes its physical state</p> Signup and view all the answers

    Why is it not essential that all substances can be changed from one state to another?

    <p>Because some substances decompose when heated</p> Signup and view all the answers

    What is the term used to describe the energy required to change a solid into a liquid?

    <p>Latent heat of fusion</p> Signup and view all the answers

    What is the term used to describe the process of gases intermixing with one another without any mechanical aid?

    <p>Diffusion</p> Signup and view all the answers

    What is the purpose of Graham's law of diffusion?

    <p>To determine the relative densities and molecular weights of gases</p> Signup and view all the answers

    What happens to the smell of ammonia when a bottle is opened in one corner of a laboratory?

    <p>It can be experienced all over the laboratory</p> Signup and view all the answers

    What is the result of heating ice, which is water in a solid state?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What are the three forms of matter that are interconvertible?

    <p>Solid, liquid, and gas</p> Signup and view all the answers

    What is the result of further heating the water after it changes into a liquid state?

    <p>It changes into a gas state</p> Signup and view all the answers

    What happens to the wax in a candle when it is lit up?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What is the purpose of diffusion in separating gases from a mixture?

    <p>To separate gases based on their molecular weights</p> Signup and view all the answers

    What is the term used to describe the process of gases spreading and intermixing with one another?

    <p>Diffusion</p> Signup and view all the answers

    What is the result of repeating the process of diffusion to separate gases from a mixture?

    <p>Gases can be completely separated</p> Signup and view all the answers

    What is the process of converting gases like nitrogen, oxygen, hydrogen, and helium into a liquid state?

    <p>Cooling and increasing pressure</p> Signup and view all the answers

    Why does sugar not change into liquid sugar when heated?

    <p>Because the sugar changes into a decomposed substance after heating</p> Signup and view all the answers

    What is the energy required to change a solid into a liquid called?

    <p>Latent heat</p> Signup and view all the answers

    What happens to the temperature of a system when it reaches the melting point?

    <p>It remains constant until all the ice melts</p> Signup and view all the answers

    What is the term for the heat supplied to change the state of a substance?

    <p>Latent heat</p> Signup and view all the answers

    Why does the heat supplied to a system not change the temperature until all the ice melts?

    <p>Because the heat is used to change the state of the system</p> Signup and view all the answers

    What is the result of altering the temperature of a substance?

    <p>It changes its state</p> Signup and view all the answers

    What can cause a gas to change its state?

    <p>Changing the pressure</p> Signup and view all the answers

    What is the energy required to change a solid into a liquid also known as?

    <p>Latent heat</p> Signup and view all the answers

    What is the purpose of latent heat in a system?

    <p>To change the state of the system</p> Signup and view all the answers

    What is the amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure without any change in temperature?

    <p>Latent heat of fusion</p> Signup and view all the answers

    What happens to the molecules of a solid when it is subjected to heating?

    <p>Their kinetic energy increases</p> Signup and view all the answers

    What is the term for the temperature at which a solid gets converted to a liquid state at atmospheric pressure?

    <p>Melting point</p> Signup and view all the answers

    What is the effect of pressure on the melting point of solids that expand on melting?

    <p>It increases the melting point</p> Signup and view all the answers

    What is the latent heat of fusion of ice?

    <p>3.34 x 10^5 J/kg</p> Signup and view all the answers

    What is the state of water at 100°C?

    <p>Vapour</p> Signup and view all the answers

    What is the effect of pressure on the melting point of solids that contract on melting?

    <p>It decreases the melting point</p> Signup and view all the answers

    What is the change in the molecular arrangement of a solid during melting?

    <p>It changes from solid to liquid</p> Signup and view all the answers

    What is the type of heat energy required to change 1 kg of a liquid into a vapour at atmospheric pressure without any change in temperature?

    <p>Latent heat of vaporization</p> Signup and view all the answers

    What is the graph of temperature against time for the change from ice at -15°C to water and further to steam?

    <p>A curved line</p> Signup and view all the answers

    What is latent heat of fusion?

    <p>The amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure</p> Signup and view all the answers

    What is the latent heat of fusion of ice?

    <p>3.34 x 10^5 J/kg</p> Signup and view all the answers

    What happens to the molecules when a solid is heated?

    <p>They absorb heat energy and increase their kinetic energy</p> Signup and view all the answers

    What is the temperature at which a solid changes to a liquid state at atmospheric pressure?

    <p>Melting point</p> Signup and view all the answers

    What happens to the melting point of a solid that expands on melting when the pressure is increased?

    <p>It increases</p> Signup and view all the answers

    What is the effect of pressure on the melting point of paraffin wax?

    <p>It increases the melting point</p> Signup and view all the answers

    What is the process by which the molecular arrangement of a solid changes to that of a liquid?

    <p>Melting</p> Signup and view all the answers

    What is the graph of temperature against time for the change from ice to water and further to steam?

    <p>A step-wise line</p> Signup and view all the answers

    What is the melting point of ice?

    <p>0°C</p> Signup and view all the answers

    What is the effect of pressure on the melting point of cast iron?

    <p>It decreases the melting point</p> Signup and view all the answers

    What is the main effect of adding impurities to a solid?

    <p>Decrease the melting point of the solid</p> Signup and view all the answers

    What is the melting point of Rose's metal?

    <p>94.5°C</p> Signup and view all the answers

    What is the process of conversion of a liquid state to a solid state called?

    <p>Freezing</p> Signup and view all the answers

    What is the unique property of ice that makes it less dense than water?

    <p>Its molecules form a latticework of hexagons</p> Signup and view all the answers

    Why do fish and aquatic animals survive in frozen lakes?

    <p>Because ice is less dense than water</p> Signup and view all the answers

    What is the freezing point of a liquid?

    <p>The temperature at which a liquid converts into a solid at atmospheric pressure</p> Signup and view all the answers

    What is the main reason why ice floats on water?

    <p>Because ice is less dense than water</p> Signup and view all the answers

    What is the density of ice?

    <p>0.917 g/cm3</p> Signup and view all the answers

    What is the main problem caused by the expansion of ice on land?

    <p>All of the above</p> Signup and view all the answers

    What is the percentage of ice that remains below the water's surface?

    <p>90%</p> Signup and view all the answers

    What is the effect of adding impurities to a solid?

    <p>Decrease the melting point of the solid</p> Signup and view all the answers

    What is the melting point of Rose's metal?

    <p>94.5°C</p> Signup and view all the answers

    What is the freezing point of a liquid?

    <p>The temperature at which a liquid converts into a solid</p> Signup and view all the answers

    Why does ice float on water?

    <p>Because it is less dense than water</p> Signup and view all the answers

    What is the density of ice?

    <p>0.917 g/cm³</p> Signup and view all the answers

    Why can fish survive in frozen lakes?

    <p>Because ice is less dense than water</p> Signup and view all the answers

    What happens to the volume of water when it freezes?

    <p>It increases by 77%</p> Signup and view all the answers

    What is the main reason for the weathering of paved surfaces?

    <p>The expansion of ice</p> Signup and view all the answers

    What is the purpose of freezing mixtures?

    <p>To preserve food</p> Signup and view all the answers

    What is the composition of a freezing mixture used to produce a lower temperature?

    <p>3 parts of ice and 1 part of common salt</p> Signup and view all the answers

    What is the process by which a liquid changes into a gaseous state by absorbing heat energy called?

    <p>Boiling</p> Signup and view all the answers

    What is the quantity of heat in joules required to convert 1 kilogram of a liquid to vapour or gas, without any change in temperature?

    <p>Latent heat of vaporization</p> Signup and view all the answers

    What is the conversion formula from Celsius to Kelvin scale?

    <p>K = °C + 273</p> Signup and view all the answers

    What is the boiling point of a liquid defined as?

    <p>The constant temperature at which a liquid rapidly changes into a gaseous state by absorbing heat energy at atmospheric pressure</p> Signup and view all the answers

    What is the latent heat of vaporization of water?

    <p>22.5 x 10^5 J/kg</p> Signup and view all the answers

    What is the conversion formula from Fahrenheit to Celsius scale?

    <p>°C = (°F - 32) x 5/9</p> Signup and view all the answers

    What is the temperature at which vapour pressure of a liquid becomes equal to atmospheric pressure?

    <p>Boiling point</p> Signup and view all the answers

    What is the process by which a liquid changes into a solid state by releasing heat energy called?

    <p>Freezing</p> Signup and view all the answers

    What is the conversion formula from Kelvin to Celsius scale?

    <p>°C = K - 273</p> Signup and view all the answers

    What is the unit of latent heat of vaporization?

    <p>J/kg</p> Signup and view all the answers

    What is the process called when a liquid changes into a gaseous state by absorbing heat energy?

    <p>Boiling</p> Signup and view all the answers

    What is the latent heat of vaporization of water?

    <p>22.5 x 10^3 J/kg</p> Signup and view all the answers

    What is the temperature in Celsius when the temperature in Kelvin is 573 K?

    <p>300°C</p> Signup and view all the answers

    What is the formula to convert Fahrenheit to Celsius?

    <p>(F - 32) * 5/9</p> Signup and view all the answers

    What is the boiling point of a liquid?

    <p>The constant temperature at which the liquid rapidly changes into a gaseous state</p> Signup and view all the answers

    What is the relationship between the vapour pressure of a liquid and the atmospheric pressure at the boiling point?

    <p>The vapour pressure is equal to the atmospheric pressure</p> Signup and view all the answers

    What is the result of converting 108°F to Celsius?

    <p>42.2°C</p> Signup and view all the answers

    What is the temperature in Kelvin when the temperature in Celsius is 27°C?

    <p>300 K</p> Signup and view all the answers

    What is the latent heat of vaporization of a liquid?

    <p>The quantity of heat required to change the state of a liquid to a gas</p> Signup and view all the answers

    What is the correct conversion of 300 K to Celsius?

    <p>27°C</p> Signup and view all the answers

    What is the process by which water vapour in the air condenses into dew or frost?

    <p>Condensation</p> Signup and view all the answers

    What happens when the air becomes saturated with water vapour?

    <p>Condensation occurs</p> Signup and view all the answers

    What is the term for the temperature at which the air becomes saturated with water vapour?

    <p>Dew point</p> Signup and view all the answers

    What is the phenomenon by which a substance changes directly from solid to gas without going through the liquid phase?

    <p>Sublimation</p> Signup and view all the answers

    What type of particles can condensation occur on to form fog or mist?

    <p>Dust particles</p> Signup and view all the answers

    What is the term for the formation of water droplets in the upper part of the atmosphere?

    <p>Clouds</p> Signup and view all the answers

    What is an example of a substance that exhibits sublimation?

    <p>All of the above</p> Signup and view all the answers

    What is the result of the condensation of water vapour on floating dust particles?

    <p>Fog or mist</p> Signup and view all the answers

    What is the opposite process of condensation?

    <p>Evaporation</p> Signup and view all the answers

    What is the term for the process by which a liquid changes directly into a gas or vapour?

    <p>Evaporation</p> Signup and view all the answers

    What happens to the boiling point of a liquid when the external pressure is increased?

    <p>It increases</p> Signup and view all the answers

    Why does food cook faster in a pressure cooker?

    <p>Due to the increase in steam generated</p> Signup and view all the answers

    What is the effect of adding impurities to a liquid on its boiling point?

    <p>It increases the boiling point</p> Signup and view all the answers

    Why does it take longer to cook food in the hills?

    <p>Due to the lower atmospheric pressure</p> Signup and view all the answers

    What is the process of changing a gas or vapour into a liquid by cooling?

    <p>Condensation</p> Signup and view all the answers

    What happens to the kinetic energy of particles when a gas or vapour is cooled?

    <p>It decreases</p> Signup and view all the answers

    What is the result of the attractive forces between particles when a gas or vapour is cooled?

    <p>The particles attract each other and condense</p> Signup and view all the answers

    Why does water boil at a lower temperature at higher altitudes?

    <p>Due to the lower atmospheric pressure</p> Signup and view all the answers

    What is the effect of pressure on the boiling point of a liquid?

    <p>It increases the boiling point</p> Signup and view all the answers

    What is the effect of increasing external pressure on the boiling point of a liquid?

    <p>It increases</p> Signup and view all the answers

    What happens to the boiling point of a liquid when a solid substance is dissolved in it?

    <p>It increases</p> Signup and view all the answers

    Why does it take longer to cook food in the hills than in the plains?

    <p>Because of low air pressure</p> Signup and view all the answers

    What is the process of changing a gas or vapour to a liquid by cooling?

    <p>Condensation</p> Signup and view all the answers

    At what temperature does water boil at sea level?

    <p>373 K</p> Signup and view all the answers

    What is the effect of external pressure on the boiling point of a liquid?

    <p>It increases the boiling point</p> Signup and view all the answers

    What is the result of condensation of water vapor on floating dust particles?

    <p>Fog or mist formation</p> Signup and view all the answers

    Why does food cook faster in a pressure cooker?

    <p>Because of high pressure</p> Signup and view all the answers

    What happens to the kinetic energy of particles when a gas or vapour is cooled?

    <p>It decreases</p> Signup and view all the answers

    What is the term used to describe the temperature at which the air becomes saturated with water vapor?

    <p>Dew point</p> Signup and view all the answers

    What is the process by which a substance changes directly from the solid to the gaseous state?

    <p>Sublimation</p> Signup and view all the answers

    What is the result of the attractive forces between particles in a gas or vapour when it is cooled?

    <p>The particles come close together</p> Signup and view all the answers

    What is an example of a substance that exhibits sublimation?

    <p>All of the above</p> Signup and view all the answers

    What is the result of condensation of water vapor in the upper part of the atmosphere?

    <p>Cloud formation</p> Signup and view all the answers

    What is the process by which water in water bodies evaporates during the day?

    <p>Evaporation</p> Signup and view all the answers

    What happens to the air when the temperature falls during nighttime?

    <p>It becomes saturated with water vapor</p> Signup and view all the answers

    What is the result of further cooling of the air after it becomes saturated with water vapor?

    <p>Dew formation</p> Signup and view all the answers

    What is the process by which water droplets condense as dew?

    <p>Condensation</p> Signup and view all the answers

    What is an example of a situation where condensation occurs?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of increasing external pressure on the boiling point of a liquid?

    <p>It increases the boiling point</p> Signup and view all the answers

    Why does food cook faster in a pressure cooker?

    <p>Because the steam generated increases the pressure</p> Signup and view all the answers

    What happens when a solid substance is dissolved in a liquid?

    <p>The boiling point of the liquid increases</p> Signup and view all the answers

    What is the process by which water vapor changes directly into a solid state?

    <p>Sublimation</p> Signup and view all the answers

    What is the term for the temperature at which the air becomes saturated with water vapor?

    <p>Dew point</p> Signup and view all the answers

    Why does it take longer to cook food in the hills than in the plains?

    <p>Because the boiling point of the liquid is lower in the hills</p> Signup and view all the answers

    What is the process of changing a gas or vapour to a liquid by cooling?

    <p>Condensation</p> Signup and view all the answers

    What is the result of the condensation of water vapor on floating dust particles?

    <p>Fog or mist formation</p> Signup and view all the answers

    What is the state of matter that is characterized by random continuous motion?

    <p>Gas</p> Signup and view all the answers

    What happens when the kinetic energy of particles decreases?

    <p>The particles move slower</p> Signup and view all the answers

    What is the effect of increasing the pressure on the boiling point of a liquid at sea level?

    <p>The boiling point increases</p> Signup and view all the answers

    What is the process by which water in water bodies changes into water vapor?

    <p>Evaporation</p> Signup and view all the answers

    Why does water boil at a lower temperature in the hills than at sea level?

    <p>Because the pressure is less in the hills</p> Signup and view all the answers

    What is the result of the condensation of water vapor in the upper part of the atmosphere?

    <p>Cloud formation</p> Signup and view all the answers

    What is the reason why a pressure cooker can cook food faster than a normal vessel?

    <p>Because the steam generated increases the pressure</p> Signup and view all the answers

    What is an example of a substance that exhibits sublimation?

    <p>Ammonium chloride</p> Signup and view all the answers

    What is the state of matter that is characterized by particles that are closely packed and have a fixed shape?

    <p>Solid</p> Signup and view all the answers

    What is the process by which water vapor changes into a liquid state?

    <p>Condensation</p> Signup and view all the answers

    What is the result of the condensation of water vapor on a surface?

    <p>Dew formation</p> Signup and view all the answers

    What happens when carbon dioxide is cooled under high pressure?

    <p>It turns directly into dry ice.</p> Signup and view all the answers

    Why does dry ice not wet the surface it is kept on?

    <p>Because it sublimes.</p> Signup and view all the answers

    What is the name under which dry ice is used as a refrigerant?

    <p>Dricold</p> Signup and view all the answers

    What is the process by which iodine changes directly from a solid to a gas?

    <p>Sublimation</p> Signup and view all the answers

    What is deposited on the upper part of a test tube when iodine sublimes?

    <p>A grey powder</p> Signup and view all the answers

    What is the term for a substance that can exist in a gaseous state under specific conditions?

    <p>Vapour</p> Signup and view all the answers

    What happens to the spaces between gaseous particles when pressure is applied?

    <p>They decrease in size.</p> Signup and view all the answers

    What happens to a liquefied gas if the pressure is further increased and the temperature is further lowered?

    <p>It turns into a solid.</p> Signup and view all the answers

    What is the term for the process of a liquid changing into a vapour state even below its boiling point?

    <p>Evaporation</p> Signup and view all the answers

    Under ordinary circumstances, what state of matter will a substance remain as at room temperature and one atmospheric pressure?

    <p>Gas</p> Signup and view all the answers

    What is the reason why surface molecules of a liquid possess higher kinetic energies than the molecules in the bulk?

    <p>Due to the random motion of the molecules</p> Signup and view all the answers

    What happens when the molecules of a liquid break away from the forces of attraction of the other molecules?

    <p>They go into vapour state</p> Signup and view all the answers

    What is the state of matter that iodine turns into when heated?

    <p>Vapour</p> Signup and view all the answers

    What is the energy associated with the motion of molecules?

    <p>Kinetic energy</p> Signup and view all the answers

    What is the process by which a liquid changes into a vapour state?

    <p>Vaporization</p> Signup and view all the answers

    What is the state of matter that oxygen remains as at room temperature and one atmospheric pressure?

    <p>Gas</p> Signup and view all the answers

    What is the reason why a substance remains as a gas at room temperature and one atmospheric pressure?

    <p>Due to its ordinary circumstances</p> Signup and view all the answers

    What happens to solid iodine when it is heated?

    <p>It turns into a vapour</p> Signup and view all the answers

    What is the process of a liquid changing into a vapour state below its boiling point called?

    <p>Evaporation</p> Signup and view all the answers

    What is the reason why surface molecules in a liquid can break away and turn into vapour?

    <p>They have higher kinetic energies</p> Signup and view all the answers

    What remains the same for a substance that exists as a gas under ordinary circumstances?

    <p>Its chemical composition</p> Signup and view all the answers

    What is the state of a substance that can change into a vapour state even without heat energy?

    <p>Liquid</p> Signup and view all the answers

    What is the force that holds molecules together in a liquid?

    <p>Forces of attraction</p> Signup and view all the answers

    What is the reason why solid carbon dioxide is called dry ice?

    <p>It directly gets converted into the gaseous state without passing through the intervening liquid state</p> Signup and view all the answers

    What is the characteristic of iodine that makes it a sublimable substance?

    <p>It changes directly into a gaseous state without first melting</p> Signup and view all the answers

    What happens to the kinetic energy of particles in a substance when it is heated?

    <p>It increases</p> Signup and view all the answers

    What is the term for the process of a liquid changing into a gas at its boiling point?

    <p>Vaporization</p> Signup and view all the answers

    What is the effect of applying pressure on gases?

    <p>The spaces between the gaseous particles decrease</p> Signup and view all the answers

    What happens when a liquefied gas is subjected to further increased pressure and lowered temperature?

    <p>It changes into a solid state</p> Signup and view all the answers

    Why do surface molecules in a liquid have higher kinetic energies?

    <p>Because of their random motion</p> Signup and view all the answers

    What is the term for a substance that exists in a gaseous state under specific conditions?

    <p>Vapour</p> Signup and view all the answers

    What is the characteristic of naphthalene balls that makes them useful for preserving clothes?

    <p>They change directly into a gaseous state without wetting the clothes</p> Signup and view all the answers

    What is the process by which iodine changes directly into a gaseous state when heated?

    <p>Sublimation</p> Signup and view all the answers

    What is the characteristic of dry ice that makes it different from ordinary ice?

    <p>It does not wet the surface on which it is kept</p> Signup and view all the answers

    What is the effect of increasing the temperature of a liquid on its rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    Which factor slows down the rate of evaporation?

    <p>High humidity</p> Signup and view all the answers

    What is the result of the molecules of a liquid absorbing energy from the surroundings during evaporation?

    <p>The surroundings lose energy</p> Signup and view all the answers

    Why do different liquids have different rates of evaporation?

    <p>Due to their different interparticle attractive forces</p> Signup and view all the answers

    What happens to the molecules of a liquid when they move from an area of higher pressure to an area of lower pressure?

    <p>They are sucked into the surrounding area</p> Signup and view all the answers

    What is the result of evaporation on the temperature of the surroundings?

    <p>It decreases the temperature</p> Signup and view all the answers

    Why does acetone evaporate faster than water?

    <p>Due to its weaker interparticle attractive forces</p> Signup and view all the answers

    What is the effect of wind speed on the rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    Why do clothes take longer to dry in rainy season?

    <p>Due to the higher humidity</p> Signup and view all the answers

    What is the effect of increasing the surface area of a liquid on its rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    What happens to the rate of evaporation when the temperature of the liquid is increased?

    <p>It increases</p> Signup and view all the answers

    Why do wet clothes dry faster in summer than in winter?

    <p>Because of the high temperature in summer</p> Signup and view all the answers

    What happens to the rate of evaporation when the surface area of the liquid is increased?

    <p>It increases</p> Signup and view all the answers

    Why does humidity of air lower the rate of evaporation?

    <p>Because of the high humidity</p> Signup and view all the answers

    What happens to the rate of evaporation when the wind speed is increased?

    <p>It increases</p> Signup and view all the answers

    What is the effect of pressure on the rate of evaporation?

    <p>Decreased pressure increases the rate of evaporation</p> Signup and view all the answers

    Why do different liquids have different rates of evaporation?

    <p>Because of their different interparticle attractive forces</p> Signup and view all the answers

    What is the cooling effect produced due to evaporation?

    <p>The liquid molecules absorb energy from the surroundings</p> Signup and view all the answers

    What is an example of the cooling effect produced due to evaporation?

    <p>The cooling produced when alcohol is poured on the palm</p> Signup and view all the answers

    What is the principle behind the cooling effect produced due to evaporation?

    <p>The principle of energy absorption from the surroundings</p> Signup and view all the answers

    Which factor increases the rate of evaporation of a liquid?

    <p>Increase in surface area</p> Signup and view all the answers

    What happens to the molecules when the vapour pressure of the surrounding air increases to a specific level?

    <p>They evaporate slower</p> Signup and view all the answers

    Why do different liquids have different rates of evaporation?

    <p>Due to their interparticle attractive forces</p> Signup and view all the answers

    What is the result of evaporation on the surroundings?

    <p>The surroundings lose energy</p> Signup and view all the answers

    Why does acetone evaporate faster than water?

    <p>Because acetone has weaker interparticle attractive forces</p> Signup and view all the answers

    What is the principle behind the cooling effect produced when alcohol is poured on the palm?

    <p>Evaporation</p> Signup and view all the answers

    What is the result of decreasing the pressure around a liquid?

    <p>The rate of evaporation increases</p> Signup and view all the answers

    Why do clothes dry faster in summer than in winter?

    <p>Because of the higher temperature in summer</p> Signup and view all the answers

    What is the effect of wind speed on the rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    Why do clothes not dry easily in rainy season?

    <p>Because of the higher humidity</p> Signup and view all the answers

    What determines the colour of plasma glow?

    <p>The nature of the gas</p> Signup and view all the answers

    What is a Bose-Einstein condensate?

    <p>A type of super-cold superfluid</p> Signup and view all the answers

    What happens during evaporation?

    <p>Only high energy particles leave the liquid surface</p> Signup and view all the answers

    What is a characteristic of plasma?

    <p>It has neither a definite volume nor a definite shape</p> Signup and view all the answers

    What is the temperature at which molecular motion stops?

    <p>Absolute zero (0 K)</p> Signup and view all the answers

    What happens to atoms when cooled to near absolute zero?

    <p>They clump together</p> Signup and view all the answers

    What is the result of evaporation on the temperature of the remaining liquid?

    <p>It decreases the temperature</p> Signup and view all the answers

    Who predicted the Bose-Einstein condensate?

    <p>Satyendra Bose and Albert Einstein</p> Signup and view all the answers

    What is plasma composed of?

    <p>Charged particles</p> Signup and view all the answers

    Which of the following is an example of plasma?

    <p>A flame</p> Signup and view all the answers

    What is the temperature at which the first Bose-Einstein condensate was produced?

    <p>170 nK</p> Signup and view all the answers

    Why is plasma electrically conductive?

    <p>Because it is composed of charged particles</p> Signup and view all the answers

    What is the opposite of a super-hot plasma?

    <p>A super-cold superfluid</p> Signup and view all the answers

    What happens when atoms form a Bose-Einstein condensate?

    <p>They form a single entity</p> Signup and view all the answers

    What is the correct statement about plasma state?

    <p>The particles of plasma state are in the form of ionized gases.</p> Signup and view all the answers

    What is the term used to describe plasma?

    <p>Ionized gas</p> Signup and view all the answers

    What is the result of cooling atoms to near absolute zero?

    <p>The atoms become super-unexcited</p> Signup and view all the answers

    Who first identified plasma as 'radiant matter'?

    <p>Sir William Crookes</p> Signup and view all the answers

    Who produced the first Bose-Einstein condensate in 1995?

    <p>Eric Cornell, Ketterle, and Carl Wieman</p> Signup and view all the answers

    What is the primary factor that determines the colour of a plasma glow?

    <p>Temperature and nature of the gas</p> Signup and view all the answers

    What is the main reason why evaporation causes cooling?

    <p>Low energy particles are left behind</p> Signup and view all the answers

    What is the state of matter formed by atoms cooled to a temperature near absolute zero?

    <p>Bose-Einstein condensate</p> Signup and view all the answers

    What is the correct definition of plasma?

    <p>A state of matter that is created by heating and ionizing a gas</p> Signup and view all the answers

    What happens to molecular motion at a temperature of zero Kelvin?

    <p>It stops</p> Signup and view all the answers

    What is the result of atoms clumping together at super low temperatures?

    <p>A Bose-Einstein condensate forms</p> Signup and view all the answers

    What is the main characteristic of plasma that distinguishes it from a gas?

    <p>It is electrically conductive</p> Signup and view all the answers

    What is the characteristic of atoms in a Bose-Einstein condensate?

    <p>Super unexcited and super cold</p> Signup and view all the answers

    Which of the following is an example of plasma?

    <p>Flame and lightning</p> Signup and view all the answers

    What is the temperature at which the first Bose-Einstein condensate was produced?

    <p>170 nanokelvins</p> Signup and view all the answers

    What is the correct statement about the particles in plasma?

    <p>They are charged and respond strongly to electromagnetic fields</p> Signup and view all the answers

    What is the term used to describe plasma?

    <p>Ionized gas</p> Signup and view all the answers

    Who predicted the existence of Bose-Einstein condensate in the 1920s?

    <p>Satyendra Bose and Albert Einstein</p> Signup and view all the answers

    What is the main reason why plasma is electrically conductive?

    <p>Because it consists of charged particles</p> Signup and view all the answers

    What is the opposite of super-hot and super excited atoms?

    <p>Super unexcited and super cold atoms</p> Signup and view all the answers

    What happens when atoms take up the same place in a Bose-Einstein condensate?

    <p>They become a single entity</p> Signup and view all the answers

    Which of the following statements about plasma is false?

    <p>Plasma has a definite volume and shape</p> Signup and view all the answers

    What is the state of matter characterized by atoms being in a state of random continuous motion?

    <p>Gas</p> Signup and view all the answers

    What is the correct statement about evaporation and cooling?

    <p>Evaporation causes cooling</p> Signup and view all the answers

    What is the composition of a mixture?

    <p>Variable</p> Signup and view all the answers

    What happens when common salt is dissolved in water?

    <p>A mixture is formed</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>It does not have a fixed melting or boiling point</p> Signup and view all the answers

    What is steel used to make?

    <p>Rust-free, unbreakable utensils</p> Signup and view all the answers

    What is bone an example of?

    <p>A composite material</p> Signup and view all the answers

    What is wood composed of?

    <p>Cellulose mixed with lignin</p> Signup and view all the answers

    What is a composite material?

    <p>A material that combines the properties of two constituents</p> Signup and view all the answers

    What is the purpose of creating composite materials?

    <p>To get the exact properties needed for a particular job</p> Signup and view all the answers

    What is the characteristic of a mixture that makes it different from a pure substance?

    <p>It does not have a fixed composition</p> Signup and view all the answers

    What is the fundamental characteristic of a pure substance?

    <p>It is uniform or homogeneous throughout.</p> Signup and view all the answers

    What is the difference between an element and a compound?

    <p>An element is made up of only one kind of atom, while a compound is made up of only one kind of molecule.</p> Signup and view all the answers

    What is a characteristic of particles in a pure substance?

    <p>They are similar to one another.</p> Signup and view all the answers

    What is a mixture?

    <p>A material that contains two or more different kinds of particles which do not react chemically but are physically mixed in any proportion.</p> Signup and view all the answers

    What is the characteristic of a pure substance that makes it impossible to be separated into simpler particles?

    <p>It cannot be separated into simpler particles by physical processes.</p> Signup and view all the answers

    What is the term for the components or constituents of a mixture?

    <p>Pure substances</p> Signup and view all the answers

    What is the difference between a pure substance and a mixture?

    <p>A pure substance is made up of only one kind of particles, while a mixture is made up of two or more different kinds of particles.</p> Signup and view all the answers

    What is the characteristic of water that makes it a pure substance?

    <p>It has uniform composition throughout.</p> Signup and view all the answers

    What is the characteristic of a mixture?

    <p>It has a variable composition</p> Signup and view all the answers

    What is a characteristic of a composite material?

    <p>It combines the properties of two constituents</p> Signup and view all the answers

    What is steel used to make?

    <p>Rust-free utensils</p> Signup and view all the answers

    What is bone composed of?

    <p>Cellulose and lignin</p> Signup and view all the answers

    What is wood composed of?

    <p>Cellulose and lignin</p> Signup and view all the answers

    What is the difference between a mixture and a composite material?

    <p>A mixture has a variable composition, while a composite material has a fixed composition</p> Signup and view all the answers

    What is a characteristic of a pure substance?

    <p>It has a fixed melting point</p> Signup and view all the answers

    What is an example of a composite material?

    <p>All of the above</p> Signup and view all the answers

    What is the main difference between a mixture and a composite material?

    <p>A mixture has a variable composition, while a composite material has a fixed composition</p> Signup and view all the answers

    What is the characteristic of a pure substance?

    <p>It is uniform or homogenous throughout.</p> Signup and view all the answers

    What is the difference between an element and a compound?

    <p>An element is made up of atoms, while a compound is made up of molecules.</p> Signup and view all the answers

    What is the characteristic of particles in a pure substance?

    <p>They are similar to one another.</p> Signup and view all the answers

    What is a mixture?

    <p>A material that contains two or more different kinds of particles.</p> Signup and view all the answers

    What is the characteristic of a pure substance in terms of its composition?

    <p>It has a uniform composition.</p> Signup and view all the answers

    What is the main difference between a pure substance and a mixture?

    <p>A pure substance is uniform or homogenous, while a mixture is physically mixed.</p> Signup and view all the answers

    What is an example of a pure substance?

    <p>Water.</p> Signup and view all the answers

    What is the term for the components of a mixture?

    <p>Constituents.</p> Signup and view all the answers

    What is the characteristic of a pure substance?

    <p>It is uniform or homogenous throughout</p> Signup and view all the answers

    What is an element?

    <p>A pure substance made up of only one kind of atom</p> Signup and view all the answers

    What is a characteristic of particles in a pure substance?

    <p>They are similar to one another</p> Signup and view all the answers

    What is the term for the components of a mixture?

    <p>Constituents</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>It contains two or more different kinds of particles</p> Signup and view all the answers

    What is the difference between an element and a compound?

    <p>An element is made up of only one kind of atom, while a compound is made up of only one kind of molecule</p> Signup and view all the answers

    Why is water considered a pure substance?

    <p>Because it has uniform composition throughout</p> Signup and view all the answers

    What is not a characteristic of a mixture?

    <p>It is uniform or homogenous throughout</p> Signup and view all the answers

    What is the definition of a mixture?

    <p>A substance with a variable composition</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>It has a variable composition</p> Signup and view all the answers

    What is a composite material?

    <p>A material that combines the properties of two constituents</p> Signup and view all the answers

    What is steel used to make?

    <p>Unbreakable utensils</p> Signup and view all the answers

    What is bone an example of?

    <p>A composite material</p> Signup and view all the answers

    What is wood composed of?

    <p>Cellulose mixed with lignin</p> Signup and view all the answers

    What is the difference between a mixture and a pure substance?

    <p>A mixture has a variable composition, while a pure substance has a fixed composition</p> Signup and view all the answers

    What is a characteristic of a composite material?

    <p>It combines the properties of two or more constituents</p> Signup and view all the answers

    What is the primary reason for creating a composite material?

    <p>To achieve specific properties needed for a particular job</p> Signup and view all the answers

    What was Antoine Lavoisier's contribution to the field of chemistry?

    <p>He gave a useful definition of an element</p> Signup and view all the answers

    What is the modern definition of an element?

    <p>A pure substance that contains only one kind of atoms</p> Signup and view all the answers

    How many elements have been discovered so far?

    <p>118</p> Signup and view all the answers

    What is the state of matter of most elements at room temperature?

    <p>Solid</p> Signup and view all the answers

    Which two elements are known to exist in the liquid state at room temperature?

    <p>Mercury and bromine</p> Signup and view all the answers

    What is the characteristic of atoms of the same element?

    <p>They are identical in all respects</p> Signup and view all the answers

    Why was Antoine Lavoisier's definition of an element not considered absolutely correct?

    <p>Elements can be broken into simpler substances and synthesized from other elements</p> Signup and view all the answers

    What is the main difference between atoms of different elements?

    <p>They have different sizes and masses</p> Signup and view all the answers

    What is the temperature at which gallium and caesium become liquid?

    <p>Slightly above room temperature</p> Signup and view all the answers

    Which of the following elements are gaseous at room temperature?

    <p>All of the above</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>They are malleable and can be formed into thin sheets</p> Signup and view all the answers

    Which of the following metals are the most malleable?

    <p>Gold and silver</p> Signup and view all the answers

    How many types of elements are classified based on physical properties?

    <p>3</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>They are brittle and do not conduct electricity</p> Signup and view all the answers

    Which of the following elements is not a metal?

    <p>Fluorine</p> Signup and view all the answers

    What is the classification of elements based on physical properties?

    <p>Metals, non-metals, and metalloids</p> Signup and view all the answers

    What is unique about the properties of gallium and caesium?

    <p>They both become liquid at a relatively low temperature</p> Signup and view all the answers

    Who is credited with giving a useful definition of an element?

    <p>Antoine Laurent Lavoisier</p> Signup and view all the answers

    What is the current definition of an element?

    <p>A pure substance that contains only one kind of atoms</p> Signup and view all the answers

    How many elements have been discovered so far?

    <p>118</p> Signup and view all the answers

    What is the state of majority of the elements at room temperature?

    <p>Solid</p> Signup and view all the answers

    Which two elements are known to exist in the liquid state at room temperature?

    <p>Mercury and bromine</p> Signup and view all the answers

    What is the characteristic of atoms of the same element?

    <p>They are identical in all respects, size, mass, and composition</p> Signup and view all the answers

    What was the limitation of the original definition of an element given by Antoine Laurent Lavoisier?

    <p>It was proved wrong by the discovery of radioactivity</p> Signup and view all the answers

    Who was the first scientist to use the term 'element'?

    <p>Robert Boyle</p> Signup and view all the answers

    At what temperature do gallium and caesium become liquid?

    <p>Slightly above room temperature (303 K)</p> Signup and view all the answers

    What are the three types of elements classified based on physical properties?

    <p>Metals, Non-metals, and Metalloids</p> Signup and view all the answers

    What is malleability a characteristic of?

    <p>Metals</p> Signup and view all the answers

    Which of the following elements are the most malleable?

    <p>Gold and Silver</p> Signup and view all the answers

    How many elements are gaseous at room temperature?

    <p>11</p> Signup and view all the answers

    What are the names of the two most malleable metals?

    <p>Silver and Gold</p> Signup and view all the answers

    What is the characteristic of metals that means they can be hammered or beaten into thin sheets?

    <p>Malleability</p> Signup and view all the answers

    What type of elements are hydrogen, oxygen, and nitrogen?

    <p>Gases</p> Signup and view all the answers

    Which of the following elements are NOT gaseous at room temperature?

    <p>Gold and Silver</p> Signup and view all the answers

    What is the primary use of silver foil?

    <p>For decorating sweets</p> Signup and view all the answers

    What does the ductility of metals mean?

    <p>Metals can be drawn or stretched into thin wires</p> Signup and view all the answers

    Which metal is the best conductor of electricity?

    <p>Silver</p> Signup and view all the answers

    What is the characteristic of metals that makes them good reflectors?

    <p>Their shining surface</p> Signup and view all the answers

    Why are metals like sodium and potassium soft?

    <p>Because they are naturally soft</p> Signup and view all the answers

    What is the characteristic of metals that makes them hold large weights without breaking?

    <p>Their high tensile strength</p> Signup and view all the answers

    What is the use of aluminium foils in packaging?

    <p>For wrapping medicines and food items</p> Signup and view all the answers

    What is the characteristic of metals that makes them good conductors of heat?

    <p>Their high thermal conductivity</p> Signup and view all the answers

    Which metal is the poorest conductor of heat?

    <p>Lead</p> Signup and view all the answers

    Why are metals like gold and silver used for making jewellery?

    <p>Because they are ductile and lustrous</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>Having a high tensile strength</p> Signup and view all the answers

    Which of the following metals is not strong?

    <p>Sodium</p> Signup and view all the answers

    What is a common use of metals due to their sonorous property?

    <p>Making musical instruments</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>Being brittle and breaking easily</p> Signup and view all the answers

    Which of the following non-metals is a good conductor of heat and electricity?

    <p>Graphite</p> Signup and view all the answers

    What is a common characteristic of metals?

    <p>Having a high density</p> Signup and view all the answers

    Which of the following metals is a liquid at room temperature?

    <p>Mercury</p> Signup and view all the answers

    What is a characteristic of non-metals that makes them useful as insulators?

    <p>Their ability to resist heat and electricity</p> Signup and view all the answers

    What is the general trend in the melting and boiling points of metals?

    <p>They are generally high</p> Signup and view all the answers

    What is a characteristic of metals that makes them suitable for construction?

    <p>Their high tensile strength</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>Being sonorous</p> Signup and view all the answers

    What is true about sodium and potassium metals?

    <p>They are not strong and have low tensile strength</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>Being bad conductors of heat and electricity</p> Signup and view all the answers

    What is graphite used for?

    <p>Making electrodes of batteries and dry cells</p> Signup and view all the answers

    What is true about mercury?

    <p>It is a liquid at room temperature</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>Having high densities</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>Being soft</p> Signup and view all the answers

    What is a characteristic of gallium and caesium?

    <p>They become liquid at a temperature slightly above room temperature</p> Signup and view all the answers

    What is an exception to non-metals being bad conductors of heat and electricity?

    <p>All of the above</p> Signup and view all the answers

    What is steel?

    <p>An alloy of iron and carbon</p> Signup and view all the answers

    What is the primary use of silver foil?

    <p>For decorating sweets</p> Signup and view all the answers

    Which metal can be drawn into a wire of about 2 kilometre length with just 1 gram of it?

    <p>Gold</p> Signup and view all the answers

    What is the best conductor of heat among metals?

    <p>Silver</p> Signup and view all the answers

    Which metal is an excellent reflector of light and is used for silvering of mirrors?

    <p>Silver</p> Signup and view all the answers

    What is the property of metals that allows them to hold large weights without breaking?

    <p>High tensile strength</p> Signup and view all the answers

    Which metal is the poorest conductor of heat?

    <p>Lead</p> Signup and view all the answers

    What is the characteristic of metals that allows them to be shaped into thin wires or sheets?

    <p>Ductility</p> Signup and view all the answers

    Which metal is the best conductor of electricity?

    <p>Silver</p> Signup and view all the answers

    What is the general characteristic of metals regarding their hardness?

    <p>They are generally hard, but some are soft</p> Signup and view all the answers

    Which metal is used for making milk bottle caps?

    <p>Aluminium</p> Signup and view all the answers

    What is the characteristic of non-metals that makes them different from metals?

    <p>They have low tensile strength and are not sonorous</p> Signup and view all the answers

    Which of the following is NOT a characteristic of non-metals?

    <p>They are good conductors of electricity</p> Signup and view all the answers

    What is the term for elements that have properties in between those of metals and non-metals?

    <p>Metalloids</p> Signup and view all the answers

    What is the definition of a compound?

    <p>A pure substance made up of two or more elements chemically combined in a fixed proportion by mass</p> Signup and view all the answers

    What is the state of matter of bromine at room temperature?

    <p>Liquid</p> Signup and view all the answers

    What is the hardest natural substance known?

    <p>Diamond</p> Signup and view all the answers

    What is the characteristic of metalloids that makes them different from metals and non-metals?

    <p>They are brittle like non-metals</p> Signup and view all the answers

    What is the characteristic of non-metals that makes them different from metals in terms of their physical states?

    <p>They exist in all three states of matter</p> Signup and view all the answers

    What is the characteristic of solid non-metals, except for boron, graphite, and diamond?

    <p>They have low melting and boiling points</p> Signup and view all the answers

    What is the characteristic of non-metals in terms of their density?

    <p>They have low densities</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It is made up of different elements combined in a fixed proportion by mass.</p> Signup and view all the answers

    What is necessary for a compound to be formed?

    <p>A chemical reaction between elements.</p> Signup and view all the answers

    What is unique about the properties of a compound?

    <p>They are entirely different from those of its constituent elements.</p> Signup and view all the answers

    What is an example of a compound?

    <p>Iron sulphide.</p> Signup and view all the answers

    What happens when iron sulphide reacts with dilute sulphuric acid?

    <p>Hydrogen sulphide gas is formed.</p> Signup and view all the answers

    What is the difference between iron sulphide and its constituent elements?

    <p>Iron sulphide has different properties from iron and sulphur.</p> Signup and view all the answers

    What is the result of heating a mixture of iron and sulphur?

    <p>A chemical reaction occurs, forming iron sulphide.</p> Signup and view all the answers

    What is a characteristic of a chemical compound?

    <p>It is formed by a chemical reaction.</p> Signup and view all the answers

    What is the difference between a mixture and a compound?

    <p>A compound has properties that are different from its constituent elements.</p> Signup and view all the answers

    What is an example of a chemical compound that is commonly used?

    <p>All of the above.</p> Signup and view all the answers

    What is the primary condition for the formation of water from hydrogen and oxygen?

    <p>Passing an electric spark through the mixture</p> Signup and view all the answers

    What is a characteristic of a compound that distinguishes it from its constituent elements?

    <p>It has different properties from its constituent elements</p> Signup and view all the answers

    What is the process by which a compound can be separated into its constituent elements?

    <p>Electrolysis</p> Signup and view all the answers

    What is a characteristic of a compound that makes it a homogeneous substance?

    <p>It has the same properties throughout</p> Signup and view all the answers

    What is a criterion of purity of a solid compound?

    <p>It has a sharp melting point</p> Signup and view all the answers

    What is a characteristic of a compound that is involved in its formation?

    <p>A chemical bond is formed</p> Signup and view all the answers

    What is the result of impurities in a solid compound?

    <p>The melting point is decreased</p> Signup and view all the answers

    What is a characteristic of a compound that is evident in its physical properties?

    <p>It has a fixed melting point</p> Signup and view all the answers

    What is the result of electrolysis of a compound?

    <p>The compound is separated into its constituent elements</p> Signup and view all the answers

    What is a characteristic of a compound that distinguishes it from a mixture?

    <p>It is a homogeneous substance</p> Signup and view all the answers

    What is the boiling point of pure water at one atmosphere pressure?

    <p>100'C (373K)</p> Signup and view all the answers

    Why is ocean water not drinkable and cannot be used for crop irrigation?

    <p>It contains a large number of dissolved compounds</p> Signup and view all the answers

    What is the characteristic of a homogeneous mixture?

    <p>It has a uniform composition throughout</p> Signup and view all the answers

    What is an example of a heterogeneous mixture?

    <p>Milk</p> Signup and view all the answers

    What is the term for a mixture of two or more metals in the solid phase?

    <p>Alloy</p> Signup and view all the answers

    What is the characteristic of the components of a heterogeneous mixture?

    <p>They are visible to the naked eye or under a microscope</p> Signup and view all the answers

    Why is sea water's boiling point higher than 100'C (373K)?

    <p>It contains several dissolved salts</p> Signup and view all the answers

    What is the characteristic of all homogeneous mixtures?

    <p>They have a uniform composition throughout</p> Signup and view all the answers

    What is the difference between a homogeneous mixture and a heterogeneous mixture?

    <p>The composition of the mixture</p> Signup and view all the answers

    What is an example of a homogeneous mixture in the solid phase?

    <p>Alloys</p> Signup and view all the answers

    What happens when hydrogen and oxygen are simply mixed?

    <p>No reaction occurs</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It has a fixed melting point and boiling point</p> Signup and view all the answers

    Why does water extinguish fire?

    <p>Because it is neither combustible nor a supporter of combustion</p> Signup and view all the answers

    How can a compound be separated into its constituents?

    <p>By chemical means, such as electrolysis</p> Signup and view all the answers

    What is a characteristic of a pure solid compound?

    <p>It has a sharp melting point</p> Signup and view all the answers

    What is required for elements to become a compound?

    <p>A chemical bond between the atoms of elements</p> Signup and view all the answers

    What is a characteristic of a liquid compound?

    <p>It has a fixed boiling point</p> Signup and view all the answers

    What is the main reason why the boiling point of sea water is higher than that of pure water?

    <p>Because sea water contains dissolved salts and other impurities</p> Signup and view all the answers

    What is the result of chemical bonding between elements?

    <p>A compound with properties different from its constituents</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It is a homogeneous substance</p> Signup and view all the answers

    What is the term used to describe a mixture that has a uniform composition throughout?

    <p>Homogeneous mixture</p> Signup and view all the answers

    What is the result of energy being evolved or absorbed during the formation of a compound?

    <p>A chemical bond between the atoms of elements</p> Signup and view all the answers

    What is the term used to describe a mixture that does not have a uniform composition throughout?

    <p>Heterogeneous mixture</p> Signup and view all the answers

    What is an example of a homogeneous mixture in the solid phase?

    <p>All of the above</p> Signup and view all the answers

    Why is ocean water not suitable for drinking or irrigation?

    <p>Because it contains dissolved salts and other impurities</p> Signup and view all the answers

    What is the term used to describe a mixture of two or more miscible liquids?

    <p>Homogeneous mixture</p> Signup and view all the answers

    Why is rainwater considered a pure substance?

    <p>Because it contains dissolved gases from the air</p> Signup and view all the answers

    What is the term used to describe a mixture of two or more metals?

    <p>Alloy</p> Signup and view all the answers

    Why do homogeneous mixtures have a uniform composition throughout?

    <p>Because they have a single phase</p> Signup and view all the answers

    What is the main difference between homogeneous and heterogeneous mixtures?

    <p>Their composition throughout</p> Signup and view all the answers

    What is the main distinction between a pure substance and a mixture?

    <p>A pure substance has a fixed composition, while a mixture does not.</p> Signup and view all the answers

    What is an example of a heterogeneous mixture?

    <p>A mixture of salt and sand</p> Signup and view all the answers

    Why is a salt solution considered a mixture?

    <p>Because its constituents can be separated by physical processes</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>Its composition can vary</p> Signup and view all the answers

    Why is helium considered a pure substance?

    <p>Because it is an element</p> Signup and view all the answers

    What is an example of a container filled with a pure substance rather than with a mixture?

    <p>A balloon filled with helium</p> Signup and view all the answers

    Why is a salt solution homogeneous?

    <p>Because it appears uniform</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It has a fixed composition</p> Signup and view all the answers

    Why can a mixture be separated by physical processes?

    <p>Because its constituents are separable by physical processes</p> Signup and view all the answers

    What is a difference between a mixture and a compound?

    <p>A mixture has a variable composition, while a compound has a fixed composition</p> Signup and view all the answers

    Study Notes

    What is Chemistry?

    • Chemistry is the study of the composition, properties, and reactions of matter
    • It involves understanding what matter is, how it behaves, and how it changes

    What is Matter?

    • Matter refers to all substances and materials that make up the physical universe
    • It has three fundamental properties: mass, occupying space, and inertia

    Properties of Matter

    • Mass: the amount of matter in an object, which determines its weight
      • Example: a larger brick weighs more than a smaller brick because it contains more matter
    • Occupies Space: matter takes up space and cannot be occupied by other matter simultaneously
      • Example: two stools cannot occupy the same corner of a room, and two trucks cannot pass each other in a narrow lane
    • Inertia: matter resists changes in its motion or position unless acted upon by an external force
      • Example: a football will remain stationary until pushed, and will continue moving until stopped by an external force

    What is Chemistry?

    • Chemistry is the study of the composition, properties, and reactions of matter
    • It involves understanding what matter is, how it behaves, and how it changes

    What is Matter?

    • Matter refers to all substances and materials that make up the physical universe
    • It has three fundamental properties: mass, occupying space, and inertia

    Properties of Matter

    • Mass: the amount of matter in an object, which determines its weight
      • Example: a larger brick weighs more than a smaller brick because it contains more matter
    • Occupies Space: matter takes up space and cannot be occupied by other matter simultaneously
      • Example: two stools cannot occupy the same corner of a room, and two trucks cannot pass each other in a narrow lane
    • Inertia: matter resists changes in its motion or position unless acted upon by an external force
      • Example: a football will remain stationary until pushed, and will continue moving until stopped by an external force

    Gravity and Matter

    • Gravity is the force of attraction exerted by the Earth on objects, causing them to fall towards the ground.
    • The force of gravity affects everything with mass, including objects thrown upwards, which will eventually come back down to the ground.
    • Gravity is responsible for fruits falling from trees and objects having weight.

    Conservation of Mass

    • Matter cannot be destroyed or created, only transformed from one form to another.
    • The total mass of matter remains the same before and after physical and chemical changes.
    • This is demonstrated by Lavoisier's experiment, where tin metal was heated and converted into tin oxide, with the total weight remaining unchanged.

    Characteristics of Matter

    • Matter is defined as anything that has mass and occupies space.
    • Things that don't have mass or occupy space, such as heat, light, sound, electricity, and shadows, are not considered matter.
    • To determine if something is matter, check if it has weight; if it doesn't, it's not matter.

    Particles of Matter

    • All substances, including solids, liquids, and gases, are made up of constantly moving molecules, atoms, or ions.
    • The kinetic energy of these particles determines their physical behavior.
    • Evidence for particle movement includes the zig-zag motion of pollen grains in water.

    Gravity and Matter

    • Gravity is the force of attraction exerted by the Earth on objects, causing them to fall towards the ground.
    • The force of gravity affects everything with mass, including objects thrown upwards, which will eventually come back down to the ground.
    • Gravity is responsible for fruits falling from trees and objects having weight.

    Conservation of Mass

    • Matter cannot be destroyed or created, only transformed from one form to another.
    • The total mass of matter remains the same before and after physical and chemical changes.
    • This is demonstrated by Lavoisier's experiment, where tin metal was heated and converted into tin oxide, with the total weight remaining unchanged.

    Characteristics of Matter

    • Matter is defined as anything that has mass and occupies space.
    • Things that don't have mass or occupy space, such as heat, light, sound, electricity, and shadows, are not considered matter.
    • To determine if something is matter, check if it has weight; if it doesn't, it's not matter.

    Particles of Matter

    • All substances, including solids, liquids, and gases, are made up of constantly moving molecules, atoms, or ions.
    • The kinetic energy of these particles determines their physical behavior.
    • Evidence for particle movement includes the zig-zag motion of pollen grains in water.

    Brownian Motion

    • The zig-zag movement of small particles suspended in a liquid or gas due to constant collisions with fast-moving particles is called Brownian motion.
    • Brownian motion increases with temperature due to increased kinetic energy of particles of matter.

    States of Matter

    • Solids change into liquids and liquids into gases when particles gain more kinetic energy, allowing them to move apart from one another.
    • When molecules vibrate more quickly upon heating, some of them escape from the matter.

    Kinetic Molecular Theory of Matter

    • This theory states that any substance, whether solid, liquid, or gas, is made up of atoms, molecules, or ions that are in constant motion.
    • The main postulates of the kinetic theory of matter are:
      • Matter consists of molecules that are capable of free existence and retain all the chemical properties of the parent substance.
      • Molecules are always in a state of random continuous motion.
      • Molecules exert forces on one another, depending on intermolecular distances.
      • All collisions between particles of matter are perfectly elastic.
    • In solids, molecules vibrate about their average position.
    • In liquids, particles have enough free space to move about, but they still attract each other.
    • In gases, particles move about randomly, possessing kinetic energy.

    Particle Movement

    • Particles, especially in the gaseous or liquid state, move in a random (Helter-Skelter) direction.
    • Particles collide with one another elastically, with the total energy of the colliding particles remaining the same.
    • The movement is caused by the force of attraction between molecules, known as intermolecular force.

    Experiment: Diffusion of Iodine

    • The experiment demonstrates the mobility of particles of matter.
    • Iodine particles spread throughout the test tube, indicating their mobile nature.
    • The presence of iodine at the mouth of the test tube is detected using starch iodide paper, which turns blue.

    Experiment to Demonstrate Particle Mobility

    • A simple experiment involves placing a small piece of iodine in a corked glass test tube, which releases violet vapors of iodine that spread throughout the test tube.
    • When a starch iodide paper is brought near the mouth of the test tube, it turns blue, indicating the presence of iodine particles.

    Diffusion and Kinetic Molecular Theory

    • The diffusion of iodine particles demonstrates that particles are mobile and can move and spread in a confined space.
    • The kinetic molecular theory of matter explains that particles have kinetic energy, which enables them to move and mix with other particles.
    • When salt and water come into contact, their molecules mix and spread due to their kinetic energy, resulting in a uniform salty taste throughout the container.

    States of Matter and Kinetic Theory

    • The three states of matter (solids, liquids, and gases) differ in their particle packing, energy, and intermolecular forces.

    Characteristics of Solids

    • Particles are closely packed and have fixed positions.
    • Particles can only vibrate to and fro about their mean position, resulting in small energy due to motion.
    • Strong intermolecular forces hold particles together, giving solids a definite shape and volume.
    • Solids are:
      • Incompressible and highly rigid
      • Have high density
      • Do not flow (non-fluid)

    Experiment to Demonstrate Particle Mobility

    • A simple experiment involves placing a small piece of iodine in a corked glass test tube, which releases violet vapors of iodine that spread throughout the test tube.
    • When a starch iodide paper is brought near the mouth of the test tube, it turns blue, indicating the presence of iodine particles.

    Diffusion and Kinetic Molecular Theory

    • The diffusion of iodine particles demonstrates that particles are mobile and can move and spread in a confined space.
    • The kinetic molecular theory of matter explains that particles have kinetic energy, which enables them to move and mix with other particles.
    • When salt and water come into contact, their molecules mix and spread due to their kinetic energy, resulting in a uniform salty taste throughout the container.

    States of Matter and Kinetic Theory

    • The three states of matter (solids, liquids, and gases) differ in their particle packing, energy, and intermolecular forces.

    Characteristics of Solids

    • Particles are closely packed and have fixed positions.
    • Particles can only vibrate to and fro about their mean position, resulting in small energy due to motion.
    • Strong intermolecular forces hold particles together, giving solids a definite shape and volume.
    • Solids are:
      • Incompressible and highly rigid
      • Have high density
      • Do not flow (non-fluid)

    Liquids

    • Particles are loosely packed and have no fixed positions
    • Particles have considerable energy due to their motion, allowing them to move freely
    • Intermolecular forces are strong enough to keep particles within the boundaries of the liquid
    • Liquids have a definite volume but no definite shape
    • Liquids are incompressible and not rigid
    • Density is relatively high compared to gases and lower than solids
    • Liquids flow from high to low levels due to fluidity

    Gases

    • Particles are widely spaced and have no fixed positions
    • Particles have maximum energy due to their motion, allowing them to move freely
    • Intermolecular forces are very weak, holding particles together
    • Gases have neither a definite shape nor a definite volume
    • Gases are highly compressible and not rigid
    • Density is very low
    • Gases can flow in any direction due to fluidity

    Liquids

    • Particles are loosely packed and have no fixed positions
    • Particles have considerable energy due to their motion, allowing them to move freely
    • Intermolecular forces are strong enough to keep particles within the boundaries of the liquid
    • Liquids have a definite volume but no definite shape
    • Liquids are incompressible and not rigid
    • Density is relatively high compared to gases and lower than solids
    • Liquids flow from high to low levels due to fluidity

    Gases

    • Particles are widely spaced and have no fixed positions
    • Particles have maximum energy due to their motion, allowing them to move freely
    • Intermolecular forces are very weak, holding particles together
    • Gases have neither a definite shape nor a definite volume
    • Gases are highly compressible and not rigid
    • Density is very low
    • Gases can flow in any direction due to fluidity

    Characteristics of Solids

    • A wooden block is considered a solid because it has a fixed shape and is rigid, following all properties of a solid.
    • A rubber band is also considered a solid, despite changing shape when stretched, because it regains its original shape when the force is removed.

    Kinetic Model of a Solid

    • In a solid, molecules are closely packed, with negligible intermolecular space.
    • Molecules have fixed positions, with negligible movement.
    • Molecules are arranged in a definite manner.
    • There is a strong force of attraction (intermolecular force) between molecules.

    Kinetic Model of a Liquid

    • In a liquid, molecules are far apart from each other, with greater intermolecular space than in a solid.
    • The intermolecular force of attraction between molecules is not strong enough to keep them bonded to one position.
    • Molecules can move about more freely, with irregular and random motion.

    Characteristics of Solids

    • A wooden block is considered a solid because it has a fixed shape and is rigid, following all properties of a solid.
    • A rubber band is also considered a solid, despite changing shape when stretched, because it regains its original shape when the force is removed.

    Kinetic Model of a Solid

    • In a solid, molecules are closely packed, with negligible intermolecular space.
    • Molecules have fixed positions, with negligible movement.
    • Molecules are arranged in a definite manner.
    • There is a strong force of attraction (intermolecular force) between molecules.

    Kinetic Model of a Liquid

    • In a liquid, molecules are far apart from each other, with greater intermolecular space than in a solid.
    • The intermolecular force of attraction between molecules is not strong enough to keep them bonded to one position.
    • Molecules can move about more freely, with irregular and random motion.

    Surface Tension

    • Surface tension is a property of liquids due to intermolecular forces between liquid particles.
    • Liquid surface feels stretched due to surface tension.
    • Molecules in the bulk of the liquid are attracted equally on all sides, while surface molecules are subjected only to downward attractive forces.
    • This creates an imbalance of forces at the surface, resulting in surface tension.
    • Surface tension decreases with a rise in temperature.
    • The decrease in surface tension is due to increased kinetic energy of molecules, leading to decreased intermolecular forces.

    Surface Tension and Nature of Liquid

    • Surface tension is a measure of intermolecular attractive forces.
    • When attractive forces between molecules are large, surface tension is also large.
    • For example, the surface tension of a liquid is higher when the intermolecular forces are stronger.

    Viscosity

    • Viscosity is the internal friction or resistance that resists the relative motion of a liquid.
    • It is caused by molecular forces working between the molecules of the liquid.
    • Viscosity depends on the cohesive force between molecules.
    • Glycerine has more viscosity than water or alcohol due to stronger intermolecular forces.

    Viscosity and Nature of Liquid

    • Viscosity is related to the intermolecular forces in the liquid.
    • If intermolecular forces are large, viscosity will be high.
    • For example, honey is more viscous than water because of stronger intermolecular forces.

    Effect of Temperature on Viscosity

    • Viscosity of a liquid decreases with a rise in temperature.
    • As temperature increases, average kinetic energy increases, and intermolecular forces can be easily overcome.
    • Therefore, the liquid starts moving faster with increased temperature.

    Surface Tension

    • Surface tension is a property of liquids due to intermolecular forces between liquid particles.
    • Liquid surface feels stretched due to surface tension.
    • Molecules in the bulk of the liquid are attracted equally on all sides, while surface molecules are subjected only to downward attractive forces.
    • This creates an imbalance of forces at the surface, resulting in surface tension.
    • Surface tension decreases with a rise in temperature.
    • The decrease in surface tension is due to increased kinetic energy of molecules, leading to decreased intermolecular forces.

    Surface Tension and Nature of Liquid

    • Surface tension is a measure of intermolecular attractive forces.
    • When attractive forces between molecules are large, surface tension is also large.
    • For example, the surface tension of a liquid is higher when the intermolecular forces are stronger.

    Viscosity

    • Viscosity is the internal friction or resistance that resists the relative motion of a liquid.
    • It is caused by molecular forces working between the molecules of the liquid.
    • Viscosity depends on the cohesive force between molecules.
    • Glycerine has more viscosity than water or alcohol due to stronger intermolecular forces.

    Viscosity and Nature of Liquid

    • Viscosity is related to the intermolecular forces in the liquid.
    • If intermolecular forces are large, viscosity will be high.
    • For example, honey is more viscous than water because of stronger intermolecular forces.

    Effect of Temperature on Viscosity

    • Viscosity of a liquid decreases with a rise in temperature.
    • As temperature increases, average kinetic energy increases, and intermolecular forces can be easily overcome.
    • Therefore, the liquid starts moving faster with increased temperature.

    Surface Tension

    • Surface tension is a property of liquids due to intermolecular forces between liquid particles.
    • Liquid surface feels stretched due to surface tension.
    • Molecules in the bulk of the liquid are attracted equally on all sides, while surface molecules are subjected only to downward attractive forces.
    • This creates an imbalance of forces at the surface, resulting in surface tension.
    • Surface tension decreases with a rise in temperature.
    • The decrease in surface tension is due to increased kinetic energy of molecules, leading to decreased intermolecular forces.

    Surface Tension and Nature of Liquid

    • Surface tension is a measure of intermolecular attractive forces.
    • When attractive forces between molecules are large, surface tension is also large.
    • For example, the surface tension of a liquid is higher when the intermolecular forces are stronger.

    Viscosity

    • Viscosity is the internal friction or resistance that resists the relative motion of a liquid.
    • It is caused by molecular forces working between the molecules of the liquid.
    • Viscosity depends on the cohesive force between molecules.
    • Glycerine has more viscosity than water or alcohol due to stronger intermolecular forces.

    Viscosity and Nature of Liquid

    • Viscosity is related to the intermolecular forces in the liquid.
    • If intermolecular forces are large, viscosity will be high.
    • For example, honey is more viscous than water because of stronger intermolecular forces.

    Effect of Temperature on Viscosity

    • Viscosity of a liquid decreases with a rise in temperature.
    • As temperature increases, average kinetic energy increases, and intermolecular forces can be easily overcome.
    • Therefore, the liquid starts moving faster with increased temperature.

    Properties of Bromine

    • Bromine has a melting point of -7.2°C and a boiling point of 59°C.
    • At a temperature greater than -7.2°C but less than 59°C, bromine is a liquid, having a definite volume but no definite shape.

    Kinetic Model of a Gas

    • In a gas, molecules are spaced far apart with negligible intermolecular forces, allowing them to move freely within the available space.
    • Gas molecules move rapidly, possessing high kinetic energy, and constantly collide with each other and the container walls.
    • These collisions cause the molecules to change direction and speed, exerting pressure on the container walls.

    Why Gases Fill Containers Completely

    • Gas molecules have large intermolecular spaces and high kinetic energy but weak intermolecular forces, allowing them to spread throughout the container.
    • This results in gases filling the entire space of their containing vessel.

    Important Properties of Gases

    Exertion of Pressure

    • Gases exert pressure in all directions due to the bombardment of particles against the container walls.

    Homogeneous Nature

    • Gases have a uniform composition throughout, making them homogeneous in nature.

    Liquefaction

    • Gases can be liquefied by cooling and applying pressure.

    Diffusion

    • Gases can diffuse and spread out to fill their containers.

    Properties of Bromine

    • Bromine has a melting point of -7.2°C and a boiling point of 59°C.
    • At a temperature greater than -7.2°C but less than 59°C, bromine is a liquid, having a definite volume but no definite shape.

    Kinetic Model of a Gas

    • In a gas, molecules are spaced far apart with negligible intermolecular forces, allowing them to move freely within the available space.
    • Gas molecules move rapidly, possessing high kinetic energy, and constantly collide with each other and the container walls.
    • These collisions cause the molecules to change direction and speed, exerting pressure on the container walls.

    Why Gases Fill Containers Completely

    • Gas molecules have large intermolecular spaces and high kinetic energy but weak intermolecular forces, allowing them to spread throughout the container.
    • This results in gases filling the entire space of their containing vessel.

    Important Properties of Gases

    Exertion of Pressure

    • Gases exert pressure in all directions due to the bombardment of particles against the container walls.

    Homogeneous Nature

    • Gases have a uniform composition throughout, making them homogeneous in nature.

    Liquefaction

    • Gases can be liquefied by cooling and applying pressure.

    Diffusion

    • Gases can diffuse and spread out to fill their containers.

    Diffusion of Gases

    • Gases have the property of intermixing with each other without mechanical aid, forming a homogeneous mixture called diffusion.
    • Examples of diffusion include the spread of ammonia smell in a laboratory and perfume smell in a room.

    Uses of Gaseous Diffusion

    • Separation of gases: lighter gases diffuse quickly than heavier gases, allowing for separation of gases from a mixture.
    • Determination of relative densities and molecular weights of gases using Graham's law of diffusion.

    States of Matter

    • There are three states of matter: solid, liquid, and gas.
    • These states are interconvertible, but require changes in conditions such as temperature and pressure.

    Interconversion of States of Matter

    • Changes in temperature:
      • Increasing temperature: solid to liquid to gas (e.g., ice to water to steam).
      • Decreasing temperature: gas to liquid to solid.
    • Changes in pressure:
      • Increasing pressure: gas to liquid to solid.
      • Decreasing pressure: solid to liquid to gas.

    Important Points

    • Not all substances can be converted from one state to another (e.g., sugar cannot be melted into liquid sugar).
    • Latent heat (hidden heat) is the energy required to change the state of a substance, which is absorbed without changing the temperature (e.g., heat required to melt ice).
    • Examples of changed states:
      • Ice to water to steam (heating).
      • Wax (solid) to wax (liquid) to wax vapor (heating).
      • Gases (e.g., nitrogen, oxygen, hydrogen, helium) to liquid state (cooling and increasing pressure).

    Diffusion of Gases

    • Gases have the property of intermixing with each other without mechanical aid, forming a homogeneous mixture called diffusion.
    • Examples of diffusion include the spread of ammonia smell in a laboratory and perfume smell in a room.

    Uses of Gaseous Diffusion

    • Separation of gases: lighter gases diffuse quickly than heavier gases, allowing for separation of gases from a mixture.
    • Determination of relative densities and molecular weights of gases using Graham's law of diffusion.

    States of Matter

    • There are three states of matter: solid, liquid, and gas.
    • These states are interconvertible, but require changes in conditions such as temperature and pressure.

    Interconversion of States of Matter

    • Changes in temperature:
      • Increasing temperature: solid to liquid to gas (e.g., ice to water to steam).
      • Decreasing temperature: gas to liquid to solid.
    • Changes in pressure:
      • Increasing pressure: gas to liquid to solid.
      • Decreasing pressure: solid to liquid to gas.

    Important Points

    • Not all substances can be converted from one state to another (e.g., sugar cannot be melted into liquid sugar).
    • Latent heat (hidden heat) is the energy required to change the state of a substance, which is absorbed without changing the temperature (e.g., heat required to melt ice).
    • Examples of changed states:
      • Ice to water to steam (heating).
      • Wax (solid) to wax (liquid) to wax vapor (heating).
      • Gases (e.g., nitrogen, oxygen, hydrogen, helium) to liquid state (cooling and increasing pressure).

    Diffusion of Gases

    • Gases have the property of intermixing with each other without mechanical aid to form a homogeneous mixture, called diffusion
    • Examples of diffusion include the smell of ammonia spreading in a laboratory and the smell of perfume spreading in a room
    • Diffusion can be used to separate gases from a mixture, as lighter gases diffuse faster than heavier gases

    Separation of Gases

    • Diffusion can be used to separate gases from a mixture by repeating the process of diffusion
    • This process takes advantage of the difference in rates of diffusion between lighter and heavier gases

    States of Matter

    • The three states of matter are solid, liquid, and gas
    • These states are interconvertible, meaning they can be changed from one state to another and back again
    • Changes in temperature and pressure can cause these conversions

    Changes of State

    • Changes in temperature and pressure can cause changes in state
    • Examples include:
      • Ice (solid) → water (liquid) by heating above 0°C
      • Water (liquid) → vapour (gas) by heating above 100°C
      • Wax (solid) → molten wax (liquid) by heating
      • Molten wax (liquid) → wax vapour (gas) by further heating
      • Gas → liquid → solid by cooling and increasing pressure

    Latent Heat

    • Latent heat is the energy required to change the state of a substance (e.g., from solid to liquid)
    • During a change of state, the temperature of the system remains constant until all of the substance has changed state
    • The energy supplied during this process is used to break the intermolecular forces of attraction holding the substance in its original state
    • The term "latent" means "hidden" because the energy is not visible as a change in temperature

    Latent Heat

    • There are two types of latent heat: latent heat of fusion and latent heat of vaporization

    Latent Heat of Fusion

    • Defined as the amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure without any change in temperature at its melting point
    • Latent heat of fusion of ice is 3.34 x 10^5 J/kg

    Melting Process

    • When a solid is heated, molecules absorb heat energy, increasing kinetic energy and temperature
    • Further heat energy is used to break intermolecular forces of attraction, increasing intermolecular spaces, and changing the molecular arrangement from solid to liquid
    • The temperature at which a solid converts to a liquid state at atmospheric pressure is called the melting point of the solid

    Factors Affecting Melting Point

    • Effect of pressure: depends on the nature of the solid
      • For solids that expand on melting, increased pressure increases the melting point (e.g., Paraffin wax, silver, gold, and copper)
      • For solids that contract on melting, increased pressure decreases the melting point (e.g., ice, cast iron, brass)

    Latent Heat

    • There are two types of latent heat: latent heat of fusion and latent heat of vaporization

    Latent Heat of Fusion

    • Defined as the amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure without any change in temperature at its melting point
    • Latent heat of fusion of ice is 3.34 x 10^5 J/kg

    Melting Process

    • When a solid is heated, molecules absorb heat energy, increasing kinetic energy and temperature
    • Further heat energy is used to break intermolecular forces of attraction, increasing intermolecular spaces, and changing the molecular arrangement from solid to liquid
    • The temperature at which a solid converts to a liquid state at atmospheric pressure is called the melting point of the solid

    Factors Affecting Melting Point

    • Effect of pressure: depends on the nature of the solid
      • For solids that expand on melting, increased pressure increases the melting point (e.g., Paraffin wax, silver, gold, and copper)
      • For solids that contract on melting, increased pressure decreases the melting point (e.g., ice, cast iron, brass)

    Effect of Impurities on Melting Point

    • Addition of impurities to a solid decreases its melting point, allowing it to melt at a lower temperature.
    • Example: Rose's metal alloy (tin, lead, and bismuth) has a melting point of 94.5°C, lower than the individual melting points of its components: Pb (327°C), Sn (231.9°C), and Bi (271°C).

    Freezing

    • Freezing is the process of converting a liquid to a solid state, opposite to melting.
    • The temperature at which a liquid converts to a solid at atmospheric pressure is called the freezing point.
    • Factors that affect the melting point of a substance also affect its freezing point.

    Freezing Mixtures

    • A mixture of 3 parts ice and 1 part common salt is called a freezing mixture, used to produce a lower temperature (e.g., -21°C).
    • Freezing mixtures are used for preserving food, especially perishables like fish, meats, and frozen foods.

    Unique Properties of Ice

    • Ice is less dense as a solid than as a liquid, unlike most substances that become denser when frozen.
    • Water expands 7.7% in volume when it freezes, due to its molecules forming a latticework of hexagons with empty space.
    • Ice has a density of 0.917 g/cm³, while water has a maximum density of 1.00 g/cm³ at 3.98°C.
    • The expansion of ice is responsible for weathering of paved surfaces, and its unique properties allow it to float on water.

    Survival of Aquatic Animals in Frozen Lakes

    • Pure water has a maximum density at 4°C and a minimum density at 0°C.
    • Ice at 0°C has a lower density than water, causing it to float.
    • Water expands instead of compressing between 0°C and 4°C, remaining in a liquid state.
    • Oxygen is trapped beneath the layer of ice, allowing fish and aquatic animals to survive in frozen lakes.

    Effect of Impurities on Melting Point

    • Addition of impurities to a solid decreases its melting point, allowing it to melt at a lower temperature.
    • Example: Rose's metal alloy (tin, lead, and bismuth) has a melting point of 94.5°C, lower than the individual melting points of its components: Pb (327°C), Sn (231.9°C), and Bi (271°C).

    Freezing

    • Freezing is the process of converting a liquid to a solid state, opposite to melting.
    • The temperature at which a liquid converts to a solid at atmospheric pressure is called the freezing point.
    • Factors that affect the melting point of a substance also affect its freezing point.

    Freezing Mixtures

    • A mixture of 3 parts ice and 1 part common salt is called a freezing mixture, used to produce a lower temperature (e.g., -21°C).
    • Freezing mixtures are used for preserving food, especially perishables like fish, meats, and frozen foods.

    Unique Properties of Ice

    • Ice is less dense as a solid than as a liquid, unlike most substances that become denser when frozen.
    • Water expands 7.7% in volume when it freezes, due to its molecules forming a latticework of hexagons with empty space.
    • Ice has a density of 0.917 g/cm³, while water has a maximum density of 1.00 g/cm³ at 3.98°C.
    • The expansion of ice is responsible for weathering of paved surfaces, and its unique properties allow it to float on water.

    Survival of Aquatic Animals in Frozen Lakes

    • Pure water has a maximum density at 4°C and a minimum density at 0°C.
    • Ice at 0°C has a lower density than water, causing it to float.
    • Water expands instead of compressing between 0°C and 4°C, remaining in a liquid state.
    • Oxygen is trapped beneath the layer of ice, allowing fish and aquatic animals to survive in frozen lakes.

    Boiling and Latent Heat of Vaporization

    • Boiling is the process by which a liquid changes into a gaseous state by absorbing heat energy.
    • Latent heat of vaporization is the quantity of heat in joules required to convert 1 kilogram of a liquid at its boiling point to vapor or gas, without any change in temperature.
    • The latent heat of vaporization of water is 22.5 x 10^5 joules per kilogram (or 225 x 10^5 J/kg).

    Temperature Conversion

    Celsius to Kelvin Scale

    • To convert temperature from Celsius to Kelvin, add 273 to the Celsius temperature.
    • Example: 0°C = 0 + 273 = 273 K, 100°C = 100 + 273 = 373 K.

    Kelvin to Celsius Scale

    • To convert temperature from Kelvin to Celsius, subtract 273 from the Kelvin temperature.
    • Example: 373 K = 373 - 273 = 100°C, 273 K = (273 - 273) = 0°C.

    Kelvin to Fahrenheit Scale

    • To convert temperature from Kelvin to Fahrenheit, use the formula: (9/5)C + 32 = F.

    Conversions

    • Example conversions:
      • 300 K = (300 - 273) = 27°C.
      • 573 K = (573 - 273) = 300°C.
      • 27°C = 27 + 273 = 300 K.
      • 378°C = 378 + 273 = 651 K.
      • 108°F = (108 - 32) × 5/9 = 42.2°C.

    Boiling and Latent Heat of Vaporization

    • Boiling is the process by which a liquid changes into a gaseous state by absorbing heat energy.
    • Latent heat of vaporization is the quantity of heat in joules required to convert 1 kilogram of a liquid at its boiling point to vapor or gas, without any change in temperature.
    • The latent heat of vaporization of water is 22.5 x 10^5 joules per kilogram (or 225 x 10^5 J/kg).

    Temperature Conversion

    Celsius to Kelvin Scale

    • To convert temperature from Celsius to Kelvin, add 273 to the Celsius temperature.
    • Example: 0°C = 0 + 273 = 273 K, 100°C = 100 + 273 = 373 K.

    Kelvin to Celsius Scale

    • To convert temperature from Kelvin to Celsius, subtract 273 from the Kelvin temperature.
    • Example: 373 K = 373 - 273 = 100°C, 273 K = (273 - 273) = 0°C.

    Kelvin to Fahrenheit Scale

    • To convert temperature from Kelvin to Fahrenheit, use the formula: (9/5)C + 32 = F.

    Conversions

    • Example conversions:
      • 300 K = (300 - 273) = 27°C.
      • 573 K = (573 - 273) = 300°C.
      • 27°C = 27 + 273 = 300 K.
      • 378°C = 378 + 273 = 651 K.
      • 108°F = (108 - 32) × 5/9 = 42.2°C.

    Factors Affecting Boiling Point

    • The boiling point of a liquid increases with an increase in external pressure.
    • At higher altitudes, water boils at a lower temperature than 100°C due to lower pressure.
    • In a pressure cooker, the steam generated in a fixed volume increases the pressure beyond normal atmospheric pressure, allowing food to cook faster.

    Effect of Impurities

    • Adding impurities to a liquid raises its boiling point beyond the normal boiling point.
    • For example, when common salt is dissolved in water, the solution boils at a temperature greater than 100°C.

    Cooking Time at Different Altitudes

    • The boiling point of a liquid depends on the pressure acting on it.
    • At sea level, water boils at 373 K, but at higher altitudes, it boils at a lower temperature due to lower pressure.
    • Food takes longer to cook at higher altitudes because water boils at a lower temperature, requiring more time to cook.

    Condensation

    • Condensation occurs when a gas or vapour is cooled, causing the kinetic energy of its particles to decrease.
    • As the temperature is further lowered, the attractive forces pull the particles close together, and the gas or vapour condenses into a liquid.

    Effects of Condensation on Climate

    • The formation of dew, fog, and clouds are examples of condensation.
    • The temperature at which the atmospheric air becomes saturated with water vapour is called the dew point.
    • When the temperature falls below the dew point, water vapour condenses, forming dew, fog, or clouds.

    Sublimation

    • Sublimation is the phenomenon where a substance changes directly from the solid to the gaseous state without undergoing the liquid state.
    • Examples of substances that exhibit sublimation include iodine, naphthalene, solid carbon dioxide (dry ice), and ammonium chloride.

    Factors Affecting Boiling Point

    • The boiling point of a liquid increases with an increase in external pressure.
    • At higher altitudes, water boils at a lower temperature than 100°C due to lower pressure.
    • In a pressure cooker, the steam generated in a fixed volume increases the pressure beyond normal atmospheric pressure, allowing food to cook faster.

    Effect of Impurities

    • Adding impurities to a liquid raises its boiling point beyond the normal boiling point.
    • For example, when common salt is dissolved in water, the solution boils at a temperature greater than 100°C.

    Cooking Time at Different Altitudes

    • The boiling point of a liquid depends on the pressure acting on it.
    • At sea level, water boils at 373 K, but at higher altitudes, it boils at a lower temperature due to lower pressure.
    • Food takes longer to cook at higher altitudes because water boils at a lower temperature, requiring more time to cook.

    Condensation

    • Condensation occurs when a gas or vapour is cooled, causing the kinetic energy of its particles to decrease.
    • As the temperature is further lowered, the attractive forces pull the particles close together, and the gas or vapour condenses into a liquid.

    Effects of Condensation on Climate

    • The formation of dew, fog, and clouds are examples of condensation.
    • The temperature at which the atmospheric air becomes saturated with water vapour is called the dew point.
    • When the temperature falls below the dew point, water vapour condenses, forming dew, fog, or clouds.

    Sublimation

    • Sublimation is the phenomenon where a substance changes directly from the solid to the gaseous state without undergoing the liquid state.
    • Examples of substances that exhibit sublimation include iodine, naphthalene, solid carbon dioxide (dry ice), and ammonium chloride.

    Factors Affecting Boiling Point

    • Boiling point of a liquid increases with an increase in external pressure
    • Water boils at a lower temperature than 100°C at higher altitudes due to lower pressure
    • In a pressure cooker, steam generated in a fixed volume increases pressure beyond normal atmospheric pressure, resulting in faster cooking

    Effect of Impurities

    • Boiling point of a liquid increases when a solid substance is dissolved or added to the liquid
    • For example, when common salt is dissolved in water, the solution boils at a temperature greater than 100°C

    Boiling Point and Altitude

    • Boiling point of a liquid depends on the pressure acting on it
    • Water boils at 373 K at sea level where the pressure is 1 atmosphere
    • On mountains, water boils at a lower temperature due to lower pressure, resulting in longer cooking time

    Condensation

    • Condensation occurs when a gas or vapour is cooled by lowering its temperature
    • As the temperature is further lowered, particles slow down and are pulled together by attractive forces, resulting in condensation
    • Examples of condensation include the formation of dew, fog, and clouds

    Effects of Condensation on Climate

    • Dew forms when the air becomes saturated with water vapour and the temperature falls
    • Fog or mist forms when condensation occurs on floating dust particles
    • Clouds form when condensed water droplets appear in the upper part of the atmosphere

    Sublimation

    • Sublimation is the phenomenon where a substance changes directly from a solid to a gas on heating and back to a solid on cooling
    • Examples of substances that exhibit sublimation include iodine, naphthalene, solid carbon dioxide (dry ice), and ammonium chloride

    Dry Ice

    • Solid carbon dioxide (CO2) is called dry ice because it sublimes, meaning it directly changes into the gaseous state (carbon dioxide gas) without passing through the liquid state.
    • Dry ice does not wet the surface it is kept on due to this unique property.
    • Dry ice is used as a refrigerant under the name Dricold.

    Sublimation

    • Iodine is a substance that can sublime, meaning it changes from a solid to a gas without melting.
    • When heated, iodine crystals directly change into violet-colored vapors.
    • The vapors of iodine get deposited on the upper part of the test tube and appear as grey powder, known as sublimate.
    • Naphthalene balls also sublime, directly changing into vapor state without changing into a liquid.

    Properties of Gases

    • Gases are compressible because the spaces between the gaseous particles decrease when pressure is applied.
    • Gases can be compressed readily due to their compressibility.

    Effect of Pressure and Temperature

    • When the pressure on a liquefied gas is increased and the temperature is lowered, the liquefied gas can change into a solid state.

    Vapors and Gases

    • A substance that under ordinary conditions is a solid or liquid but can exist in a gaseous state under specific conditions is called a vapor.
    • Examples of vapors include water vapor and iodine vapor.
    • A substance that under ordinary circumstances exists as a gas will remain as a gas at room temperature and one atmospheric pressure.
    • Examples of gases include oxygen, nitrogen, and hydrogen.

    Evaporation

    • Evaporation is the process of converting a liquid into a gaseous state.
    • Evaporation can occur without supplying heat energy to the liquid.
    • The surface molecules of a liquid possess higher kinetic energies, allowing them to break away from the forces of attraction and change into a vapor state.
    • Evaporation can occur below a liquid's boiling point.

    Dry Ice

    • Solid carbon dioxide (CO2) is called dry ice because it sublimes, meaning it directly changes into the gaseous state (carbon dioxide gas) without passing through the liquid state.
    • Dry ice does not wet the surface it is kept on due to this unique property.
    • Dry ice is used as a refrigerant under the name Dricold.

    Sublimation

    • Iodine is a substance that can sublime, meaning it changes from a solid to a gas without melting.
    • When heated, iodine crystals directly change into violet-colored vapors.
    • The vapors of iodine get deposited on the upper part of the test tube and appear as grey powder, known as sublimate.
    • Naphthalene balls also sublime, directly changing into vapor state without changing into a liquid.

    Properties of Gases

    • Gases are compressible because the spaces between the gaseous particles decrease when pressure is applied.
    • Gases can be compressed readily due to their compressibility.

    Effect of Pressure and Temperature

    • When the pressure on a liquefied gas is increased and the temperature is lowered, the liquefied gas can change into a solid state.

    Vapors and Gases

    • A substance that under ordinary conditions is a solid or liquid but can exist in a gaseous state under specific conditions is called a vapor.
    • Examples of vapors include water vapor and iodine vapor.
    • A substance that under ordinary circumstances exists as a gas will remain as a gas at room temperature and one atmospheric pressure.
    • Examples of gases include oxygen, nitrogen, and hydrogen.

    Evaporation

    • Evaporation is the process of converting a liquid into a gaseous state.
    • Evaporation can occur without supplying heat energy to the liquid.
    • The surface molecules of a liquid possess higher kinetic energies, allowing them to break away from the forces of attraction and change into a vapor state.
    • Evaporation can occur below a liquid's boiling point.

    Factors Affecting Evaporation

    • Increasing the temperature of a liquid increases the rate of evaporation, as seen in how wet clothes dry faster in summer than in winter.
    • The rate of evaporation increases with an increase in surface area.

    Humidity of Air

    • Humidity of air, which measures the degree of dampness of air, lowers the rate of evaporation.
    • In rainy seasons, clothes take longer to dry due to high humidity.

    Wind Speed

    • The rate of evaporation of a liquid increases with increasing wind speed, as seen in how switching on a ceiling fan helps dry a wet floor faster.

    Pressure

    • Decreasing the pressure around a liquid increases the rate of evaporation, as molecules move from areas of higher to lower pressure.
    • However, if the vapor pressure of the surrounding increases to a specific level, the rate of evaporation slows down.

    Nature of Liquid

    • Different liquids have different rates of evaporation, depending on their interparticle attractive forces.
    • Liquids with weaker interparticle attractive forces, such as acetone, evaporate faster than those with stronger forces, like water.

    Cooling Produced by Evaporation

    • During evaporation, liquid molecules absorb energy from their surroundings and overcome attractive forces, changing into a vapor state.
    • As a result, the surroundings lose energy, becoming cooler.
    • Examples of cooling produced by evaporation include:
      • The cool sensation produced when alcohol is poured on the palm.
      • The cooling effect of cotton clothes in summer.
      • The formation of water droplets on the outer surface of a glass containing ice-cold water.
      • The cooling of water in earthen pots.

    Factors Affecting Evaporation

    • Increasing the temperature of a liquid increases the rate of evaporation, as seen in how wet clothes dry faster in summer than in winter.
    • The rate of evaporation increases with an increase in surface area.

    Humidity of Air

    • Humidity of air, which measures the degree of dampness of air, lowers the rate of evaporation.
    • In rainy seasons, clothes take longer to dry due to high humidity.

    Wind Speed

    • The rate of evaporation of a liquid increases with increasing wind speed, as seen in how switching on a ceiling fan helps dry a wet floor faster.

    Pressure

    • Decreasing the pressure around a liquid increases the rate of evaporation, as molecules move from areas of higher to lower pressure.
    • However, if the vapor pressure of the surrounding increases to a specific level, the rate of evaporation slows down.

    Nature of Liquid

    • Different liquids have different rates of evaporation, depending on their interparticle attractive forces.
    • Liquids with weaker interparticle attractive forces, such as acetone, evaporate faster than those with stronger forces, like water.

    Cooling Produced by Evaporation

    • During evaporation, liquid molecules absorb energy from their surroundings and overcome attractive forces, changing into a vapor state.
    • As a result, the surroundings lose energy, becoming cooler.
    • Examples of cooling produced by evaporation include:
      • The cool sensation produced when alcohol is poured on the palm.
      • The cooling effect of cotton clothes in summer.
      • The formation of water droplets on the outer surface of a glass containing ice-cold water.
      • The cooling of water in earthen pots.

    Factors Affecting Evaporation

    • The rate of evaporation increases with an increase in temperature, as seen in the faster drying of wet clothes in summer compared to winter.

    Surface Area

    • The rate of evaporation increases as the surface area of the liquid increases.

    Humidity

    • Humidity of air measures the degree of dampness of air and lowers the rate of evaporation, making it harder for clothes to dry in rainy seasons.

    Wind Speed

    • The rate of evaporation increases with an increase in wind speed, as seen in the use of ceiling fans to dry wet floors.

    Pressure

    • The rate of evaporation increases with a decrease in pressure around the liquid, as molecules move from areas of higher pressure to lower pressure to equalize the pressure.

    Nature of Liquid

    • Different liquids have different rates of evaporation, with liquids having weaker interparticle attractive forces evaporating faster (e.g., acetone evaporates faster than water).

    Cooling Produced by Evaporation

    • Evaporation absorbs energy from the surroundings, causing a cooling effect, which is utilized in various daily life activities, such as:
      • The cool sensation produced when alcohol is poured on the palm
      • The cooling effect of cotton clothes during summer
      • The formation of water droplets on the outer surface of glasses containing ice-cold water
      • The cooling of water in earthen pots

    Evaporation and Cooling

    • Evaporation causes cooling because only high-energy particles leave the liquid surface, leaving behind particles with low energy, which lowers the average molecular energy and temperature of the remaining liquid.

    Plasma: A State of Matter

    • Plasma is the fourth phase of matter, apart from solids, liquids, and gases.
    • It is formed by heating and ionizing a gas, creating a collection of charged particles that respond strongly to electromagnetic fields.
    • Plasma has unique properties, including electrical conductivity due to free electrical charges.
    • Examples of plasma can be found in nature (flames, interstellar nebulae, aurora borealis, lightning, stars) and artificially (fluorescent lights, neon signs).

    Characteristics of Plasma

    • Plasma is an "ionized gas" composed of electrically charged particles, often described as "super energetic and super excited particles".
    • The state consists of ionized gases, not super excited particles.
    • Plasma glows with a color depending on the nature of the gas, not just the temperature.

    Bose-Einstein Condensate (BEC)

    • A BEC is a gaseous superfluid phase formed by atoms cooled to temperatures near absolute zero.
    • The first BEC was produced in 1995 by Eric Cornell, Ketterle, and Carl Wieman using a gas of rubidium atoms cooled to 170 nanokelvins.
    • BEC is the opposite of plasma, consisting of "super unexcited and super cold atoms".
    • At absolute zero (0 K), molecular motion stops, and atoms clump together, forming a single "super atom" with the same qualities.

    Evaporation and Cooling

    • Evaporation causes cooling because it involves the departure of high-energy particles from the liquid surface, leaving behind particles with low energy.
    • As a result, the average molecular energy of the remaining particles in the liquid state is lowered, leading to a decrease in temperature.

    Plasma

    • Plasma is a fourth phase of matter, distinct from solids, liquids, and gases.
    • It is a collection of charged particles that respond strongly and collectively to electromagnetic fields, taking the form of gas-like clouds or ion beams.
    • Plasma is formed by heating and ionizing a gas, losing its electrons due to heat.
    • It has neither a definite volume nor a definite shape.
    • Free electrical charges in plasma make it electrically conductive.
    • Examples of plasma include flames, interstellar nebulae, aurora borealis, lightning, stars, and fluorescent lights.

    Properties of Plasma

    • Plasma is composed of charged particles, including ions and free electrons.
    • The particles in plasma are electrically charged, making it an "ionized gas".
    • The glow of plasma depends on the nature of the gas, not just the temperature.

    Bose-Einstein Condensate (BEC)

    • A BEC is a gaseous superfluid phase formed by atoms cooled to temperatures near absolute zero.
    • The first BEC was produced in 1995 by Eric Cornell, Ketterle, and Carl Wieman using a gas of rubidium atoms.
    • The BEC is formed at super low temperatures, near 0 K, where all molecular motion stops.
    • Atoms begin to clump together, forming a super atom, where thousands of separate atoms become one entity with the same qualities.

    Matter Around Us

    • Matter refers to elements, compounds, and mixtures combined.

    Pure Substances

    • A pure substance is made up of only one kind of particles (atoms or molecules).
    • A pure substance is uniform or homogenous throughout.
    • Examples of pure substances include water (made up of only one kind of particle called water molecules).
    • Pure substances have a fixed composition and a fixed melting or boiling point.
    • Based on the nature of the constituent particle, pure substances are of two types:
      • Elements: made up of only one kind of atom.
      • Compounds: made up of only one kind of molecule.

    Mixtures

    • A mixture is a material that contains two or more different kinds of particles (atoms or molecules) that do not react chemically but are physically mixed in any proportion.
    • Mixtures are impure substances.
    • Examples of mixtures include a solution of common salt (sodium chloride) in water.
    • Mixtures have a variable composition, i.e., does not have a fixed composition.
    • Mixtures do not have a fixed melting point or fixed boiling point.

    Composite Materials

    • Composite materials combine the properties of two or more constituents to achieve specific properties needed for a particular job.
    • Examples of composite materials include:
      • Steel: used to make rust-free, unbreakable utensils.
      • Bone: a composite material.
      • Wood: consists of cellulose mixed with lignin, which is largely responsible for the strength of the wood.

    Matter Around Us

    • Matter refers to elements, compounds, and mixtures combined.

    Pure Substances

    • A pure substance is made up of only one kind of particles (atoms or molecules).
    • A pure substance is uniform or homogenous throughout.
    • Examples of pure substances include water (made up of only one kind of particle called water molecules).
    • Pure substances have a fixed composition and a fixed melting or boiling point.
    • Based on the nature of the constituent particle, pure substances are of two types:
      • Elements: made up of only one kind of atom.
      • Compounds: made up of only one kind of molecule.

    Mixtures

    • A mixture is a material that contains two or more different kinds of particles (atoms or molecules) that do not react chemically but are physically mixed in any proportion.
    • Mixtures are impure substances.
    • Examples of mixtures include a solution of common salt (sodium chloride) in water.
    • Mixtures have a variable composition, i.e., does not have a fixed composition.
    • Mixtures do not have a fixed melting point or fixed boiling point.

    Composite Materials

    • Composite materials combine the properties of two or more constituents to achieve specific properties needed for a particular job.
    • Examples of composite materials include:
      • Steel: used to make rust-free, unbreakable utensils.
      • Bone: a composite material.
      • Wood: consists of cellulose mixed with lignin, which is largely responsible for the strength of the wood.

    Matter Around Us

    • Matter refers to elements, compounds, and mixtures combined.

    Pure Substances

    • A pure substance is made up of only one kind of particles (atoms or molecules).
    • A pure substance is uniform or homogenous throughout.
    • Examples of pure substances include water (made up of only one kind of particle called water molecules).
    • Pure substances have a fixed composition and a fixed melting or boiling point.
    • Based on the nature of the constituent particle, pure substances are of two types:
      • Elements: made up of only one kind of atom.
      • Compounds: made up of only one kind of molecule.

    Mixtures

    • A mixture is a material that contains two or more different kinds of particles (atoms or molecules) that do not react chemically but are physically mixed in any proportion.
    • Mixtures are impure substances.
    • Examples of mixtures include a solution of common salt (sodium chloride) in water.
    • Mixtures have a variable composition, i.e., does not have a fixed composition.
    • Mixtures do not have a fixed melting point or fixed boiling point.

    Composite Materials

    • Composite materials combine the properties of two or more constituents to achieve specific properties needed for a particular job.
    • Examples of composite materials include:
      • Steel: used to make rust-free, unbreakable utensils.
      • Bone: a composite material.
      • Wood: consists of cellulose mixed with lignin, which is largely responsible for the strength of the wood.

    Definition of Elements

    • Robert Boyle was the first to use the term "element" in 1661.
    • Antoine Lavoisier defined an element as the simplest form of a pure substance that cannot be broken or built up from simpler substances by physical or chemical methods.
    • However, this definition is no longer considered accurate due to the discovery of radioactivity and the synthesis of elements from simpler substances.
    • The modern definition of an element is a pure substance that consists of only one kind of atoms.

    Characteristics of Elements

    • An element is made up of only one kind of atoms, which are identical in all respects (size, mass, composition, etc.).
    • Atoms of different elements differ in size, mass, and composition.
    • There are 118 elements discovered so far, with 90 occurring naturally and 28 synthesized in laboratories.

    States of Elements

    • Majority of the elements are solids at room temperature (e.g., iron, copper, aluminium, silver, gold, sodium, potassium, sulphur, phosphorus, carbon).
    • Only two elements, mercury and bromine, are liquids at room temperature.
    • Gallium and caesium become liquid at a temperature slightly above room temperature (303 K).
    • Eleven elements are gaseous at room temperature (e.g., hydrogen, oxygen, nitrogen, fluorine, chlorine, helium, neon, argon, krypton, xenon, and radon).

    Classification of Elements

    • Elements can be classified into three categories based on physical properties: metals, non-metals, and metalloids.

    Physical Properties of Metals

    • Metals are malleable, meaning they can be hammered or beaten to form thin sheets without breaking.
    • Some metals are more malleable than others (e.g., gold and silver are the most malleable).

    Definition of Elements

    • Robert Boyle was the first to use the term "element" in 1661.
    • Antoine Lavoisier defined an element as the simplest form of a pure substance that cannot be broken or built up from simpler substances by physical or chemical methods.
    • However, this definition is no longer considered accurate due to the discovery of radioactivity and the synthesis of elements from simpler substances.
    • The modern definition of an element is a pure substance that consists of only one kind of atoms.

    Characteristics of Elements

    • An element is made up of only one kind of atoms, which are identical in all respects (size, mass, composition, etc.).
    • Atoms of different elements differ in size, mass, and composition.
    • There are 118 elements discovered so far, with 90 occurring naturally and 28 synthesized in laboratories.

    States of Elements

    • Majority of the elements are solids at room temperature (e.g., iron, copper, aluminium, silver, gold, sodium, potassium, sulphur, phosphorus, carbon).
    • Only two elements, mercury and bromine, are liquids at room temperature.
    • Gallium and caesium become liquid at a temperature slightly above room temperature (303 K).
    • Eleven elements are gaseous at room temperature (e.g., hydrogen, oxygen, nitrogen, fluorine, chlorine, helium, neon, argon, krypton, xenon, and radon).

    Classification of Elements

    • Elements can be classified into three categories based on physical properties: metals, non-metals, and metalloids.

    Physical Properties of Metals

    • Metals are malleable, meaning they can be hammered or beaten to form thin sheets without breaking.
    • Some metals are more malleable than others (e.g., gold and silver are the most malleable).

    Uses of Metals

    • Silver foil is used for decorating sweets.
    • Aluminium foil is used for wrapping medicines, cigarettes, and food items like biscuits and chocolates.
    • Milk bottle caps are also made up of aluminium foil.
    • Sheets of iron, copper, and aluminium are used for making utensils, containers, and bodies of automobiles.

    Physical Properties of Metals

    • Metals are ductile, meaning they can be drawn or stretched into thin wires.
    • Gold and silver are the most ductile metals.
    • Gold is so ductile that 1 gram of it can be drawn to form a wire of about 2 kilometer length.
    • Metals are good conductors of heat, with copper being the best conductor after silver.
    • Lead is the poorest conductor of heat.
    • Metals are good conductors of electricity, with silver being the best conductor.
    • Copper, gold, and aluminium are also good conductors of electricity.
    • Metals like lead and mercury offer very high resistance to the flow of electric current and are poor conductors of electricity.
    • Metals are lustrous due to their shining surface, making them good reflectors.
    • Silver metal is an excellent reflector of light and is used for silvering of mirrors.
    • Metals are generally hard, but some metals like sodium and potassium are soft and can be easily cut with a knife.
    • Metals have high tensile strength, meaning they can hold large weights without breaking.
    • Steel is an alloy of iron and carbon and is very strong, making it suitable for construction of buildings, bridges, and machines.
    • Metals are generally solids at room temperature, except for mercury which is a liquid.
    • Metals generally have high melting and boiling points, except for sodium and potassium which have low melting points.
    • Metals generally have high densities, except for sodium and potassium which have low densities.
    • Metals are sonorous, meaning they make a ringing sound when hit, making them suitable for making musical instruments.

    Physical Properties of Non-Metals

    • Non-metals are not malleable but are brittle, meaning they cannot be hammered or beaten to form thin sheets.
    • Non-metals are not ductile, meaning they cannot be drawn or stretched into wires.
    • Non-metals are bad conductors of heat and electricity, making them insulators.
    • Diamond is an allotropic form of carbon that is a good conductor of heat but bad conductor of electricity.
    • Graphite is another allotropic form of carbon that is a good conductor of heat and electricity and is used for making electrodes of batteries and dry cells.
    • Non-metals are not lustrous but have a dull appearance, except for iodine and graphite which have shining surfaces.
    • Non-metals are generally soft.

    Uses of Metals

    • Silver foil is used for decorating sweets.
    • Aluminium foil is used for wrapping medicines, cigarettes, and food items like biscuits and chocolates.
    • Milk bottle caps are also made up of aluminium foil.
    • Sheets of iron, copper, and aluminium are used for making utensils, containers, and bodies of automobiles.

    Physical Properties of Metals

    • Metals are ductile, meaning they can be drawn or stretched into thin wires.
    • Gold and silver are the most ductile metals.
    • Gold is so ductile that 1 gram of it can be drawn to form a wire of about 2 kilometer length.
    • Metals are good conductors of heat, with copper being the best conductor after silver.
    • Lead is the poorest conductor of heat.
    • Metals are good conductors of electricity, with silver being the best conductor.
    • Copper, gold, and aluminium are also good conductors of electricity.
    • Metals like lead and mercury offer very high resistance to the flow of electric current and are poor conductors of electricity.
    • Metals are lustrous due to their shining surface, making them good reflectors.
    • Silver metal is an excellent reflector of light and is used for silvering of mirrors.
    • Metals are generally hard, but some metals like sodium and potassium are soft and can be easily cut with a knife.
    • Metals have high tensile strength, meaning they can hold large weights without breaking.
    • Steel is an alloy of iron and carbon and is very strong, making it suitable for construction of buildings, bridges, and machines.
    • Metals are generally solids at room temperature, except for mercury which is a liquid.
    • Metals generally have high melting and boiling points, except for sodium and potassium which have low melting points.
    • Metals generally have high densities, except for sodium and potassium which have low densities.
    • Metals are sonorous, meaning they make a ringing sound when hit, making them suitable for making musical instruments.

    Physical Properties of Non-Metals

    • Non-metals are not malleable but are brittle, meaning they cannot be hammered or beaten to form thin sheets.
    • Non-metals are not ductile, meaning they cannot be drawn or stretched into wires.
    • Non-metals are bad conductors of heat and electricity, making them insulators.
    • Diamond is an allotropic form of carbon that is a good conductor of heat but bad conductor of electricity.
    • Graphite is another allotropic form of carbon that is a good conductor of heat and electricity and is used for making electrodes of batteries and dry cells.
    • Non-metals are not lustrous but have a dull appearance, except for iodine and graphite which have shining surfaces.
    • Non-metals are generally soft.

    Non-Metals

    • Non-metals are not strong and have low tensile strength
    • Non-metals can exist in all three states of matter: solid, liquid, and gas
    • Examples of solid non-metals include boron, carbon, sulphur, and phosphorus
    • Bromine is a liquid non-metal, while hydrogen, oxygen, nitrogen, and chlorine are gaseous non-metals
    • Solid non-metals have relatively low melting and boiling points, except for boron, graphite, and diamond
    • Non-metals have low densities and are generally light elements
    • Non-metals exist in different colors, such as sulphur (yellow), phosphorus (white, yellow, or red), and chlorine (yellowish green)
    • Non-metals are not sonorous

    Metalloids

    • Metalloids are elements that have properties in between those of metals and non-metals
    • Examples of metalloids include boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), astatine (At), and polonium (Po)
    • Metalloids show some properties of metals and some properties of non-metals
    • Metalloids are brittle like non-metals and are generally semi-conductors of electricity

    Compounds

    • A compound is a pure substance made up of two or more elements chemically combined in a fixed proportion by mass
    • Examples of compounds include water (H2O), methane (CH4), silica or sand (SiO2), ammonia (NH3), and others
    • A compound is formed because of a chemical change (or reaction) and its properties are entirely different from those of its constituents
    • A chemical compound cannot be formed simply by mixing constituent elements; it is formed only when a chemical reaction takes place between them

    Formation of Compounds

    • Water is not formed when hydrogen and oxygen are simply mixed, but rather when an electric spark is passed through the mixture.
    • The properties of water are different from its constituent elements, e.g., hydrogen is combustible, oxygen supports combustion, but water is neither combustible nor a supporter of combustion.

    Characteristics of Compounds

    • A compound cannot be separated into its constituents by simple physical means, such as filtration, evaporation, distillation, solvent extraction, or using a magnet.
    • A compound has a definite molecular formula and fixed melting point and boiling point.
    • Energy in the form of heat or light is usually evolved or absorbed when a compound is formed.
    • A compound is a homogeneous substance, meaning every part of it looks alike and has the same properties.

    Criteria of Purity of Compounds

    • A solid compound is said to be pure if it has a sharp melting point, i.e., the whole of the solid melts within a range of 0.5°C or 0.5 K.
    • A liquid compound is said to be pure if it has a fixed boiling point, i.e., the whole of the liquid distils at a fixed temperature.
    • Impurities lower or depress the melting points of solid compounds and raise the boiling points of liquid compounds.

    Types of Mixtures

    • Most of the matter around us is not pure but is actually a mixture of two or more pure substances.
    • Examples of mixtures include air, milk, and ocean water.

    Homogeneous Mixtures

    • A homogeneous mixture has a uniform composition throughout.
    • The components of a homogeneous mixture are not visible to the naked eye nor even under a microscope.
    • Examples of homogeneous mixtures include:
      • Solutions of sugar in water or other liquids
      • Mixtures of two or more miscible liquids
      • Alloys, such as brass and steel

    Heterogeneous Mixtures

    • A heterogeneous mixture does not have a uniform composition throughout.
    • The components of a heterogeneous mixture are either visible to the naked eye or under a microscope.
    • There are visible boundaries of separation between the components of a heterogeneous mixture.

    Formation of Compounds

    • Water is not formed when hydrogen and oxygen are simply mixed, but rather when an electric spark is passed through the mixture.
    • The properties of water are different from those of its constituent elements, e.g., hydrogen is combustible, oxygen is a supporter of combustion, and water is neither combustible nor a supporter of combustion.
    • A compound cannot be separated into its constituents by simple physical means, but can be done by chemical means, such as electrolysis.

    Characteristics of Compounds

    • A compound has a definite molecular formula and fixed melting point and boiling point.
    • Energy in the form of heat or light is usually evolved or absorbed when a compound is formed.
    • A compound is a homogeneous substance, meaning every part of it looks alike and has the same properties.

    Criteria of Purity of Compounds

    • A solid compound is said to be pure if it has a sharp melting point, i.e., whole of the solid melts within a range of 0.5°C or 0.5 K.
    • A liquid compound is said to be pure if it has a fixed boiling point, i.e., whole of the liquid distills at a fixed temperature.
    • Impurities lower or depress the melting points of solid compounds, while impurities raise the boiling points of liquid compounds.

    Types of Mixtures

    • Homogeneous mixtures have a uniform composition throughout, and the components are not visible to the naked eye or under a microscope.
    • Examples of homogeneous mixtures include:
      • Solutions of sugar in water
      • Mixtures of two or more miscible liquids
      • Alloys (e.g., brass, steel)
    • Heterogeneous mixtures do not have a uniform composition throughout, and the components are either visible to the naked eye or under a microscope.
    • Heterogeneous mixtures have two or more distinct phases.

    Types of Mixtures

    • A mixture of sugar and sand is a heterogeneous mixture because different parts of the mixture have different sugar-sand compositions.
    • Examples of heterogeneous mixtures include iodized salt, gun powder (sulphur + charcoal + KNO3), and suspensions of solids in liquids (e.g., chalk or sand particles in water).

    Pure Substances

    • A container filled with a pure substance is a balloon filled with helium, which is an element.
    • Air, salt water, and chocolate milk are examples of mixtures or impure substances.

    Homogeneity and Mixtures

    • Compounds are homogeneous, but mixtures can be homogeneous or heterogeneous.
    • Homogeneity alone cannot be used to decide between a mixture and a compound.
    • Homogeneous mixtures, such as solutions of common salt, sugar, copper sulphate, etc. in water, are still regarded as mixtures because:
      • They show the properties of their constituents.
      • The constituents can be separated by physical processes, such as distillation.
      • The composition of the mixture is variable, and different amounts of the substance can be dissolved in the same amount of water.
      • The mixture does not have a definite formula.
      • The mixture does not have a fixed boiling point.

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    This quiz introduces the basics of chemistry, covering the concept of matter and its properties. Learn about the changes that occur in materials and why they exist.

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