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 (B)</p> Signup and view all the answers

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

<p>It contains less matter (D)</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 (C)</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 (D)</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 (C)</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 (C)</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 (C)</p> Signup and view all the answers

What is the primary focus of chemistry?

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

What is a fundamental characteristic of all matter?

<p>It has mass (D)</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 (B)</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 (D)</p> Signup and view all the answers

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

<p>Mass (B)</p> Signup and view all the answers

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

<p>Inertia (A)</p> Signup and view all the answers

How do we know that air is matter?

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

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

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

What is the primary way that matter behaves?

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

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

<p>Gravity (C)</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 (D)</p> Signup and view all the answers

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

<p>Movement or motion (C)</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 (A)</p> Signup and view all the answers

What is not considered as matter?

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

What is the origin of the word 'kinetic'?

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

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

<p>Because of their different movements (D)</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 (A)</p> Signup and view all the answers

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

<p>Gravity (B)</p> Signup and view all the answers

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

<p>Mass (A)</p> Signup and view all the answers

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

<p>Motion (D)</p> Signup and view all the answers

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

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

What is the origin of the word 'kinetic'?

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

What is not considered as matter?

<p>All of the above (D)</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 (B)</p> Signup and view all the answers

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

<p>Gravity (C)</p> Signup and view all the answers

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

<p>Motion (B)</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 (B)</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 (D)</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 (B)</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 (C)</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 (C)</p> Signup and view all the answers

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

<p>Intermolecular force (A)</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 (B)</p> Signup and view all the answers

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

<p>Motion (B)</p> Signup and view all the answers

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

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

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

<p>Random and zig-zag (C)</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. (B)</p> Signup and view all the answers

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

<p>Intermolecular force (C)</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. (A)</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. (A)</p> Signup and view all the answers

What does the diffusion of iodine particles indicate?

<p>The particles are mobile. (A)</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. (B)</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. (B)</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. (B)</p> Signup and view all the answers

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

<p>They are elastic. (A)</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. (B)</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. (A)</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. (B)</p> Signup and view all the answers

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

<p>All of the above. (D)</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. (A)</p> Signup and view all the answers

Why do solids have a definite shape and volume?

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

Why do solids have high density?

<p>Due to their closely packed particles. (D)</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. (B)</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. (A)</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. (A)</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 (B)</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 (A)</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 (A)</p> Signup and view all the answers

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

<p>All of the above (D)</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 (A)</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 (B)</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 (D)</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 (B)</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 (C)</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 (C)</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 (B)</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 (C)</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 (C)</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 (C)</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 (D)</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 (B)</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 (B)</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 (A)</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 (C)</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 (C)</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 (B)</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 (D)</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 (A)</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 (A)</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 (D)</p> Signup and view all the answers

What is a characteristic of molecules in a liquid?

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

What is a characteristic of molecules in a solid state?

<p>They have a fixed position (D)</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 (C)</p> Signup and view all the answers

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

<p>Molecules have a fixed position (A)</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 (C)</p> Signup and view all the answers

What is a characteristic of the molecules in a solid?

<p>They are closely packed (C)</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 (D)</p> Signup and view all the answers

Why is a wooden block considered a solid?

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

What is the main characteristic of a solid?

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

What is the arrangement of molecules in a solid?

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

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

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

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

<p>Viscosity (C)</p> Signup and view all the answers

Which of the following liquids is more viscous?

<p>Honey (A)</p> Signup and view all the answers

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

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

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

<p>Friction (C)</p> Signup and view all the answers

What is the relationship between intermolecular forces and viscosity?

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

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

<p>It decreases (C)</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 (D)</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 (B)</p> Signup and view all the answers

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

<p>Viscosity (C)</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 (D)</p> Signup and view all the answers

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

<p>It decreases them (C)</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 (A)</p> Signup and view all the answers

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

<p>It has strong intermolecular forces (C)</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 (B)</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 (D)</p> Signup and view all the answers

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

<p>It decreases (B)</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 (C)</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 (C)</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 (D)</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 (B)</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 (C)</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 (D)</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 (C)</p> Signup and view all the answers

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

<p>Highest (C)</p> Signup and view all the answers

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

<p>Viscosity (D)</p> Signup and view all the answers

Why does glycerine have more viscosity than water or alcohol?

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

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

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

What is the characteristics of a liquid with high viscosity?

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

What is the relation between intermolecular forces and viscosity?

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

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

<p>Stronger intermolecular forces (A)</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 (B)</p> Signup and view all the answers

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

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

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

<p>It decreases (B)</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 (B)</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 (D)</p> Signup and view all the answers

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

<p>Viscosity (A)</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 (B)</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 (D)</p> Signup and view all the answers

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

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

Why do clothes get washed more efficiently in hot water?

<p>Because of decreased surface tension (D)</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 (C)</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 (B)</p> Signup and view all the answers

Why does glycerine have more viscosity than water or alcohol?

<p>Glycerine has a higher intermolecular force (A)</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 (B)</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 (D)</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 (D)</p> Signup and view all the answers

What is the characteristic of a liquid with high viscosity?

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

What is the relationship between intermolecular forces and viscosity?

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

What is the characteristic of a liquid with low viscosity?

<p>It flows easily and quickly (C)</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 (B)</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 (A)</p> Signup and view all the answers

What is true about the composition of gases?

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

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

<p>It becomes a liquid (D)</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 (B)</p> Signup and view all the answers

What is the direction of pressure exerted by a gas?

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

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

<p>Diffusion (D)</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 (C)</p> Signup and view all the answers

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

<p>They move randomly (A)</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 (D)</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 (A)</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 (D)</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 (B)</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 (B)</p> Signup and view all the answers

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

<p>Liquefaction (A)</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 (A)</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 (B)</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 (D)</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 (A)</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 (B)</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 (D)</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 (A)</p> Signup and view all the answers

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

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

What are the three states of matter that are interconvertible?

<p>Solid, liquid, and gas (D)</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 (D)</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 (C)</p> Signup and view all the answers

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

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

What happens when a candle is lit up?

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

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

<p>Diffusion (C)</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 (C)</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 (A)</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 (C)</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 (B)</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 (C)</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 (A)</p> Signup and view all the answers

Why can sugar not be converted from solid to liquid?

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

What happens when the temperature of a substance is changed?

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

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

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

Why is latent heat called 'hidden heat'?

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

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

<p>The gas becomes a liquid (D)</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 (C)</p> Signup and view all the answers

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

<p>Diffusion (C)</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 (D)</p> Signup and view all the answers

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

<p>Separation (A)</p> Signup and view all the answers

What are the three main states of matter?

<p>Solid, Liquid, Gas (D)</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 (C)</p> Signup and view all the answers

What is the result of heating ice?

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

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

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

What happens when a candle is lit?

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

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

<p>Diffusion (C)</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 (D)</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 (C)</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 (D)</p> Signup and view all the answers

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

<p>Latent heat (D)</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 (A)</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 (D)</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 (C)</p> Signup and view all the answers

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

<p>Its physical properties change (D)</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 (A)</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 (A)</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 (A)</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 (A)</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 (C)</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 (A)</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 (C)</p> Signup and view all the answers

What are the three forms of matter that are interconvertible?

<p>Solid, liquid, and gas (C)</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 (B)</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 (C)</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 (C)</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 (C)</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 (B)</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 (C)</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 (A)</p> Signup and view all the answers

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

<p>Latent heat (A)</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 (D)</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 (B)</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 (B)</p> Signup and view all the answers

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

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

What can cause a gas to change its state?

<p>Changing the pressure (C)</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 (D)</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 (C)</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 (C)</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 (B)</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 (A)</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 (D)</p> Signup and view all the answers

What is the latent heat of fusion of ice?

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

What is the state of water at 100°C?

<p>Vapour (C)</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 (C)</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 (C)</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 (D)</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 (C)</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 (C)</p> Signup and view all the answers

What is the latent heat of fusion of ice?

<p>3.34 x 10^5 J/kg (B)</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 (C)</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 (D)</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 (C)</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 (D)</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 (D)</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 (A)</p> Signup and view all the answers

What is the melting point of ice?

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

What is the melting point of Rose's metal?

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

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

<p>Freezing (C)</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 (A)</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 (D)</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 (C)</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 (C)</p> Signup and view all the answers

What is the density of ice?

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

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

<p>90% (D)</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 (A)</p> Signup and view all the answers

What is the melting point of Rose's metal?

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

Why does ice float on water?

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

What is the density of ice?

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

Why can fish survive in frozen lakes?

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

What happens to the volume of water when it freezes?

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

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

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

What is the purpose of freezing mixtures?

<p>To preserve food (B)</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 (D)</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 (B)</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 (A)</p> Signup and view all the answers

What is the conversion formula from Celsius to Kelvin scale?

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

What is the latent heat of vaporization of water?

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

What is the conversion formula from Fahrenheit to Celsius scale?

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

What is the conversion formula from Kelvin to Celsius scale?

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

What is the unit of latent heat of vaporization?

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

What is the latent heat of vaporization of water?

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

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

<p>300°C (B), 300°C (C)</p> Signup and view all the answers

What is the formula to convert Fahrenheit to Celsius?

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

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

<p>42.2°C (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 (B)</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 (D)</p> Signup and view all the answers

What is the correct conversion of 300 K to Celsius?

<p>27°C (B), 27°C (D)</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 (B)</p> Signup and view all the answers

What happens when the air becomes saturated with water vapour?

<p>Condensation occurs (D)</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 (A)</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 (C)</p> Signup and view all the answers

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

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

What is an example of a substance that exhibits sublimation?

<p>All of the above (D)</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 (C)</p> Signup and view all the answers

What is the opposite process of condensation?

<p>Evaporation (D)</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 (A)</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 (A)</p> Signup and view all the answers

Why does food cook faster in a pressure cooker?

<p>Due to the increase in steam generated (A)</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 (C)</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 (D)</p> Signup and view all the answers

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

<p>Condensation (B)</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 (A)</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 (B)</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 (B)</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 (C)</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 (C)</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 (B)</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 (A)</p> Signup and view all the answers

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

<p>Condensation (A)</p> Signup and view all the answers

At what temperature does water boil at sea level?

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

Why does food cook faster in a pressure cooker?

<p>Because of high pressure (B)</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 (D)</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 (C)</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 (C)</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 (A)</p> Signup and view all the answers

What is an example of a substance that exhibits sublimation?

<p>All of the above (D)</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 (A)</p> Signup and view all the answers

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

<p>Evaporation (C)</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 (B)</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 (D)</p> Signup and view all the answers

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

<p>Condensation (A)</p> Signup and view all the answers

What is an example of a situation where condensation occurs?

<p>All of the above (D)</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 (C)</p> Signup and view all the answers

Why does food cook faster in a pressure cooker?

<p>Because the steam generated increases the pressure (B)</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 (D)</p> Signup and view all the answers

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

<p>Sublimation (B)</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 (B)</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 (A)</p> Signup and view all the answers

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

<p>Condensation (A)</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 (C)</p> Signup and view all the answers

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

<p>Gas (D)</p> Signup and view all the answers

What happens when the kinetic energy of particles decreases?

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

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

<p>Evaporation (B)</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 (D)</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 (A)</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 (D)</p> Signup and view all the answers

What is an example of a substance that exhibits sublimation?

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

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

<p>Condensation (A)</p> Signup and view all the answers

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

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

What happens when carbon dioxide is cooled under high pressure?

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

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

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

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

<p>Dricold (A)</p> Signup and view all the answers

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

<p>Sublimation (A)</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 (A)</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 (C)</p> Signup and view all the answers

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

<p>They decrease in size. (C)</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. (D)</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 (D)</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 (A)</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 (D)</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 (D)</p> Signup and view all the answers

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

<p>Vapour (D)</p> Signup and view all the answers

What is the energy associated with the motion of molecules?

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

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

<p>Vaporization (B)</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 (D)</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 (A)</p> Signup and view all the answers

What happens to solid iodine when it is heated?

<p>It turns into a vapour (A)</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 (B)</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 (D)</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 (D)</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 (C)</p> Signup and view all the answers

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

<p>Forces of attraction (A)</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 (B)</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 (C)</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 (D)</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 (A)</p> Signup and view all the answers

What is the effect of applying pressure on gases?

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

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

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

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

<p>Sublimation (D)</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 (D)</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 (C)</p> Signup and view all the answers

Which factor slows down the rate of evaporation?

<p>High humidity (B)</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 (A)</p> Signup and view all the answers

Why do different liquids have different rates of evaporation?

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

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

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

Why does acetone evaporate faster than water?

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

Why do clothes take longer to dry in rainy season?

<p>Due to the higher humidity (A)</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 (B)</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 (B)</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 (C)</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 (D)</p> Signup and view all the answers

Why does humidity of air lower the rate of evaporation?

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

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

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

Why do different liquids have different rates of evaporation?

<p>Because of their different interparticle attractive forces (D)</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 (C)</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 (B)</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 (D)</p> Signup and view all the answers

Which factor increases the rate of evaporation of a liquid?

<p>Increase in surface area (A)</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 (D)</p> Signup and view all the answers

Why do different liquids have different rates of evaporation?

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

What is the result of evaporation on the surroundings?

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

Why does acetone evaporate faster than water?

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

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

<p>The rate of evaporation increases (C)</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 (D)</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 (B)</p> Signup and view all the answers

Why do clothes not dry easily in rainy season?

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

What determines the colour of plasma glow?

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

What is a Bose-Einstein condensate?

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

What happens during evaporation?

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

What is a characteristic of plasma?

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

What is the temperature at which molecular motion stops?

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

What happens to atoms when cooled to near absolute zero?

<p>They clump together (D)</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 (A)</p> Signup and view all the answers

Who predicted the Bose-Einstein condensate?

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

What is plasma composed of?

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

Which of the following is an example of plasma?

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

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

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

Why is plasma electrically conductive?

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

What is the opposite of a super-hot plasma?

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

What happens when atoms form a Bose-Einstein condensate?

<p>They form a single entity (C)</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. (C)</p> Signup and view all the answers

What is the term used to describe plasma?

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

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

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

Who first identified plasma as 'radiant matter'?

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

Who produced the first Bose-Einstein condensate in 1995?

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

What is the main reason why evaporation causes cooling?

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

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

<p>It stops (A)</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 (C)</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 (A)</p> Signup and view all the answers

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

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

Which of the following is an example of plasma?

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

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

<p>170 nanokelvins (C)</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 (D)</p> Signup and view all the answers

What is the term used to describe plasma?

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

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

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

What is the main reason why plasma is electrically conductive?

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

Which of the following statements about plasma is false?

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

What is the correct statement about evaporation and cooling?

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

What is the composition of a mixture?

<p>Variable (A)</p> Signup and view all the answers

What happens when common salt is dissolved in water?

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

What is steel used to make?

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

What is bone an example of?

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

What is wood composed of?

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

What is a composite material?

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

What is the fundamental characteristic of a pure substance?

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

What is a characteristic of particles in a pure substance?

<p>They are similar to one another. (C)</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. (B)</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. (B)</p> Signup and view all the answers

What is the term for the components or constituents of a mixture?

<p>Pure substances (B)</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. (A)</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. (A)</p> Signup and view all the answers

What is the characteristic of a mixture?

<p>It has a variable composition (C)</p> Signup and view all the answers

What is a characteristic of a composite material?

<p>It combines the properties of two constituents (B)</p> Signup and view all the answers

What is steel used to make?

<p>Rust-free utensils (D)</p> Signup and view all the answers

What is bone composed of?

<p>Cellulose and lignin (A)</p> Signup and view all the answers

What is wood composed of?

<p>Cellulose and lignin (D)</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 (A)</p> Signup and view all the answers

What is a characteristic of a pure substance?

<p>It has a fixed melting point (B)</p> Signup and view all the answers

What is an example of a composite material?

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

What is the characteristic of a pure substance?

<p>It is uniform or homogenous throughout. (D)</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. (D)</p> Signup and view all the answers

What is the characteristic of particles in a pure substance?

<p>They are similar to one another. (C)</p> Signup and view all the answers

What is a mixture?

<p>A material that contains two or more different kinds of particles. (D)</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. (A)</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. (C)</p> Signup and view all the answers

What is an example of a pure substance?

<p>Water. (D)</p> Signup and view all the answers

What is the term for the components of a mixture?

<p>Constituents. (A)</p> Signup and view all the answers

What is the characteristic of a pure substance?

<p>It is uniform or homogenous throughout (C)</p> Signup and view all the answers

What is an element?

<p>A pure substance made up of only one kind of atom (C)</p> Signup and view all the answers

What is a characteristic of particles in a pure substance?

<p>They are similar to one another (A)</p> Signup and view all the answers

What is the term for the components of a mixture?

<p>Constituents (B)</p> Signup and view all the answers

What is a characteristic of a mixture?

<p>It contains two or more different kinds of particles (C)</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 (D)</p> Signup and view all the answers

Why is water considered a pure substance?

<p>Because it has uniform composition throughout (B)</p> Signup and view all the answers

What is not a characteristic of a mixture?

<p>It is uniform or homogenous throughout (B)</p> Signup and view all the answers

What is the definition of a mixture?

<p>A substance with a variable composition (C)</p> Signup and view all the answers

What is a characteristic of a mixture?

<p>It has a variable composition (B)</p> Signup and view all the answers

What is a composite material?

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

What is steel used to make?

<p>Unbreakable utensils (A)</p> Signup and view all the answers

What is bone an example of?

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

What is wood composed of?

<p>Cellulose mixed with lignin (B)</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 (D)</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 (B)</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 (A)</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 (B)</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 (A)</p> Signup and view all the answers

How many elements have been discovered so far?

<p>118 (A)</p> Signup and view all the answers

What is the state of matter of most elements at room temperature?

<p>Solid (D)</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 (A)</p> Signup and view all the answers

What is the characteristic of atoms of the same element?

<p>They are identical in all respects (D)</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 (D)</p> Signup and view all the answers

What is the main difference between atoms of different elements?

<p>They have different sizes and masses (C)</p> Signup and view all the answers

What is the temperature at which gallium and caesium become liquid?

<p>Slightly above room temperature (C)</p> Signup and view all the answers

Which of the following elements are gaseous at room temperature?

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

What is a characteristic of metals?

<p>They are malleable and can be formed into thin sheets (D)</p> Signup and view all the answers

Which of the following metals are the most malleable?

<p>Gold and silver (D)</p> Signup and view all the answers

How many types of elements are classified based on physical properties?

<p>3 (D)</p> Signup and view all the answers

What is a characteristic of non-metals?

<p>They are brittle and do not conduct electricity (C)</p> Signup and view all the answers

Which of the following elements is not a metal?

<p>Fluorine (C)</p> Signup and view all the answers

What is the classification of elements based on physical properties?

<p>Metals, non-metals, and metalloids (C)</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 (D)</p> Signup and view all the answers

Who is credited with giving a useful definition of an element?

<p>Antoine Laurent Lavoisier (A)</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 (B)</p> Signup and view all the answers

How many elements have been discovered so far?

<p>118 (B)</p> Signup and view all the answers

What is the state of majority of the elements at room temperature?

<p>Solid (B)</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 (A)</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 (D)</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 (C)</p> Signup and view all the answers

Who was the first scientist to use the term 'element'?

<p>Robert Boyle (B)</p> Signup and view all the answers

At what temperature do gallium and caesium become liquid?

<p>Slightly above room temperature (303 K) (D)</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 (C)</p> Signup and view all the answers

What is malleability a characteristic of?

<p>Metals (A)</p> Signup and view all the answers

Which of the following elements are the most malleable?

<p>Gold and Silver (A)</p> Signup and view all the answers

How many elements are gaseous at room temperature?

<p>11 (A)</p> Signup and view all the answers

What are the names of the two most malleable metals?

<p>Silver and Gold (C)</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 (C)</p> Signup and view all the answers

What type of elements are hydrogen, oxygen, and nitrogen?

<p>Gases (D)</p> Signup and view all the answers

Which of the following elements are NOT gaseous at room temperature?

<p>Gold and Silver (B)</p> Signup and view all the answers

What is the primary use of silver foil?

<p>For decorating sweets (A)</p> Signup and view all the answers

What does the ductility of metals mean?

<p>Metals can be drawn or stretched into thin wires (C)</p> Signup and view all the answers

Which metal is the best conductor of electricity?

<p>Silver (A)</p> Signup and view all the answers

What is the characteristic of metals that makes them good reflectors?

<p>Their shining surface (B)</p> Signup and view all the answers

Why are metals like sodium and potassium soft?

<p>Because they are naturally soft (C)</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 (B)</p> Signup and view all the answers

What is the use of aluminium foils in packaging?

<p>For wrapping medicines and food items (A)</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 (A)</p> Signup and view all the answers

Which metal is the poorest conductor of heat?

<p>Lead (D)</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 (A)</p> Signup and view all the answers

What is a characteristic of metals?

<p>Having a high tensile strength (A)</p> Signup and view all the answers

Which of the following metals is not strong?

<p>Sodium (B)</p> Signup and view all the answers

What is a common use of metals due to their sonorous property?

<p>Making musical instruments (C)</p> Signup and view all the answers

What is a characteristic of non-metals?

<p>Being brittle and breaking easily (D)</p> Signup and view all the answers

Which of the following non-metals is a good conductor of heat and electricity?

<p>Graphite (A)</p> Signup and view all the answers

What is a common characteristic of metals?

<p>Having a high density (B)</p> Signup and view all the answers

Which of the following metals is a liquid at room temperature?

<p>Mercury (D)</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 (C)</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 (A)</p> Signup and view all the answers

What is a characteristic of metals that makes them suitable for construction?

<p>Their high tensile strength (C)</p> Signup and view all the answers

What is a characteristic of metals?

<p>Being sonorous (B)</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 (C)</p> Signup and view all the answers

What is a characteristic of non-metals?

<p>Being bad conductors of heat and electricity (C)</p> Signup and view all the answers

What is graphite used for?

<p>Making electrodes of batteries and dry cells (A)</p> Signup and view all the answers

What is true about mercury?

<p>It is a liquid at room temperature (B)</p> Signup and view all the answers

What is a characteristic of metals?

<p>Having high densities (A)</p> Signup and view all the answers

What is a characteristic of non-metals?

<p>Being soft (D)</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 (C)</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 (D)</p> Signup and view all the answers

What is steel?

<p>An alloy of iron and carbon (C)</p> Signup and view all the answers

What is the primary use of silver foil?

<p>For decorating sweets (A)</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 (C)</p> Signup and view all the answers

What is the best conductor of heat among metals?

<p>Silver (B)</p> Signup and view all the answers

Which metal is an excellent reflector of light and is used for silvering of mirrors?

<p>Silver (B)</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 (A)</p> Signup and view all the answers

Which metal is the poorest conductor of heat?

<p>Lead (C)</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 (A)</p> Signup and view all the answers

Which metal is the best conductor of electricity?

<p>Silver (B)</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 (B)</p> Signup and view all the answers

Which metal is used for making milk bottle caps?

<p>Aluminium (B)</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 (B)</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 (D)</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 (C)</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 (A)</p> Signup and view all the answers

What is the state of matter of bromine at room temperature?

<p>Liquid (D)</p> Signup and view all the answers

What is the hardest natural substance known?

<p>Diamond (B)</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 (A)</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 (D)</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 (D)</p> Signup and view all the answers

What is the characteristic of non-metals in terms of their density?

<p>They have low densities (B)</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. (A)</p> Signup and view all the answers

What is necessary for a compound to be formed?

<p>A chemical reaction between elements. (B)</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. (C)</p> Signup and view all the answers

What is an example of a compound?

<p>Iron sulphide. (B)</p> Signup and view all the answers

What happens when iron sulphide reacts with dilute sulphuric acid?

<p>Hydrogen sulphide gas is formed. (C)</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. (D)</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. (D)</p> Signup and view all the answers

What is a characteristic of a chemical compound?

<p>It is formed by a chemical reaction. (B)</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. (C)</p> Signup and view all the answers

What is an example of a chemical compound that is commonly used?

<p>All of the above. (D)</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 (A)</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 (D)</p> Signup and view all the answers

What is the process by which a compound can be separated into its constituent elements?

<p>Electrolysis (C)</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 (D)</p> Signup and view all the answers

What is a criterion of purity of a solid compound?

<p>It has a sharp melting point (A)</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 (A)</p> Signup and view all the answers

What is the result of impurities in a solid compound?

<p>The melting point is decreased (A)</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 (B)</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 (A)</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 (B)</p> Signup and view all the answers

What is the boiling point of pure water at one atmosphere pressure?

<p>100'C (373K) (B)</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 (D)</p> Signup and view all the answers

What is the characteristic of a homogeneous mixture?

<p>It has a uniform composition throughout (D)</p> Signup and view all the answers

What is an example of a heterogeneous mixture?

<p>Milk (A)</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 (A)</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 (D)</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 (A)</p> Signup and view all the answers

What is the characteristic of all homogeneous mixtures?

<p>They have a uniform composition throughout (A)</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 (C)</p> Signup and view all the answers

What is an example of a homogeneous mixture in the solid phase?

<p>Alloys (D)</p> Signup and view all the answers

What happens when hydrogen and oxygen are simply mixed?

<p>No reaction occurs (D)</p> Signup and view all the answers

What is a characteristic of a compound?

<p>It has a fixed melting point and boiling point (A)</p> Signup and view all the answers

Why does water extinguish fire?

<p>Because it is neither combustible nor a supporter of combustion (A)</p> Signup and view all the answers

How can a compound be separated into its constituents?

<p>By chemical means, such as electrolysis (C)</p> Signup and view all the answers

What is a characteristic of a pure solid compound?

<p>It has a sharp melting point (C)</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 (D)</p> Signup and view all the answers

What is a characteristic of a liquid compound?

<p>It has a fixed boiling point (C)</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 (B)</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 (A)</p> Signup and view all the answers

What is a characteristic of a compound?

<p>It is a homogeneous substance (B)</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 (A)</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 (C)</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 (B)</p> Signup and view all the answers

What is an example of a homogeneous mixture in the solid phase?

<p>All of the above (D)</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 (B)</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 (B)</p> Signup and view all the answers

Why is rainwater considered a pure substance?

<p>Because it contains dissolved gases from the air (A)</p> Signup and view all the answers

What is the term used to describe a mixture of two or more metals?

<p>Alloy (D)</p> Signup and view all the answers

Why do homogeneous mixtures have a uniform composition throughout?

<p>Because they have a single phase (A)</p> Signup and view all the answers

What is the main difference between homogeneous and heterogeneous mixtures?

<p>Their composition throughout (A)</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. (A)</p> Signup and view all the answers

What is an example of a heterogeneous mixture?

<p>A mixture of salt and sand (B)</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 (C)</p> Signup and view all the answers

What is a characteristic of a mixture?

<p>Its composition can vary (B)</p> Signup and view all the answers

Why is helium considered a pure substance?

<p>Because it is an element (B)</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 (B)</p> Signup and view all the answers

Why is a salt solution homogeneous?

<p>Because it appears uniform (D)</p> Signup and view all the answers

What is a characteristic of a compound?

<p>It has a fixed composition (D)</p> Signup and view all the answers

Why can a mixture be separated by physical processes?

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What is a difference between a mixture and a compound?

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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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