Class 9 Next Year Questions PDF

Class IX “Next Year Questions” Is Matter Around Us Pure PRASHANT KIRAD PRASHANT KIRAD Q1. Which of the following is not a homogeneous mixture? (a) Air (b) Tincture of iodine (c) Sugar solution (d) milk Q2. Sol and Gel are examples of (a) Solid-solid colloids (b) Sol...

Class IX “Next Year Questions” Is Matter Around Us Pure PRASHANT KIRAD PRASHANT KIRAD Q1. Which of the following is not a homogeneous mixture? (a) Air (b) Tincture of iodine (c) Sugar solution (d) milk Q2. Sol and Gel are examples of (a) Solid-solid colloids (b) Sol is a solid-liquid colloid and Gel is liquid solid colloid (c) Sol is a solid-solid colloid and Gel is a solid-liquid colloid (d) Sol is a liquid-solid colloid and Gel is a solid-liquid colloid Q3.Which of the statements is incorrect about the physical change? (a) There is no gain or loss of energy. (b) It is permanent and Irreversible (c) Composition of the substance remains the same (d) No new substance is formed. Q4. In sugar solution, (a) Sugar is solute, water is solvent (b) Sugar is solvent, water is solute (c) Both are solutes (d) Both are solvents. Q5. Mixture can be (a) homogeneous (b) heterogeneous (c) Both (a) and (b) (d) pure substance Q6. Explain the following giving examples: (a) Saturated solution PRASHANT KIRAD (b) Pure substance (c) Colloid (d) Suspension Q 7. Differentiate between a mixture and a compound with at least three points of distinction. Q8. 0.5 g of salt is dissolved in 25 g of water. Calculate the percentage amount of the salt in the solution. Q9(a) Under which category of mixtures will you classify alloys and why? (b) A solution is always a liquid. Comment. Q10. What is the Tyndall effect? Which kind of solutions show it? Q11.What is a suspension? What are the properties of suspension? Q12.Differentiate between homogenous and heterogeneous mixtures with examples. Q13.What are the two components of a colloidal solution? Q14.Name the process associated with the following: (a) Dry ice is kept at room temperature and at one atmospheric pressure. (b) A potassium permanganate crystal is in a beaker and water is poured into the beaker with stirring. (c) An acetone bottle is left open and the bottle becomes empty. (d) Milk is churned to separate cream from it. (e) Settling of sand when a mixture of sand and water is left undisturbed for some time. (f) Fine beam of light entering through a small hole in a dark room, illuminates the particles in its paths. Q15. Why is the Tyndall effect not observed in a true solution? Explain with an example. 9th Phodenge! PRASHANT KIRAD SOLUTION Ans1. d Ans2.b Ans3.b Ans4.a Ans5.c Ans6.(a) Saturated solution: In a given solvent when no more solute can dissolve further at a given temperature is called saturated solution. (b) Pure substance: A pure substance consists of a single type of particles. E.g., gold, silver. (c) Colloid: A colloid is a solution in which the size of solute particles are bigger than that of true solution. These particles cannot be seen with our naked eyes, they are stable, e.g., ink, blood. (d) Suspension: It is a heterogeneous mixture in which the solute particles are big enough to settle down, e.g., chalk-water, paints, etc. Ans7. Property Mixture Compound Components can vary in any Components are in a fixed ratio Composition proportion. by mass. Components can be separated by Components cannot be Separation physical methods. separated by physical methods. Retains the properties of Has properties different from Properties individual components. its constituent elements. Ans8. Mass of salt present = 0.5 g Mass of water present in solution = 25 g ∴ Percentage amount of the salt = (0.5/0.5+25)×100 = 1.96% PRASHANT KIRAD Ans9.(a) Alloys are homogeneous mixture of two or more elements because the constituent elements mix together and give a mixture which is uniform throughout. (b) No, solid solutions and gaseous solutions are also possible. Examples are brass, air. Ans10. Tyndall effect is a process in which the scattering of beams of light takes place in particles of a colloid, when that is directed towards them. Heterogeneous mixtures like, Suspension solution and colloidal solution show the Tyndall effect. Ans11.A suspension is a heterogeneous mixture in which the solute particles do not dissolve in the solvent but they remain suspended throughout the bulk of the medium. The suspension particle size is large enough to be visible from naked eyes. Properties of suspension: The particles are large so can be seen by naked eyes. They scatter a beam of light passing through it. When particles are left undisturbed, they settle down. Ans12. Ans13.The two components of a colloidal solution are dispersed phase and dispersing medium. Ans14.(a) Sublimation (b) Dissolution/diffusion (c) Evaporation/diffusion (d) Centrifugation (e) Sedimentation (f) Scattering of light (Tyndall effect). PRASHANT KIRAD Ans15 The Tyndall effect is the scattering of light by particles in a colloid or a very fine suspension. It is not observed in a true solution because the particles in a true solution are extremely small, with sizes less than 1 nm. These particles are too small to scatter light and allow it to pass through without deflection. Example: A sugar solution is a true solution, and when light passes through it, no scattering occurs, so the Tyndall effect is not observed. Conversely, in milk (a colloid), light is scattered, showing the Tyndall effect.  Class IX “Next Year Questions” Matter in our Surroundings PRASHANT KIRAD PRASHANT KIRAD Q1. What happens to the arrangement of particles when a substance changes from solid to liquid state? A) Particles come closer together B) Particles move further apart C) Particles become arranged in a regular pattern D) None of the above Q2. Which of the following statement is correct? (a) Substances that exist as liquids at room temperature typically have melting and boiling points lower than that of room temperature. (b) The process in which a substance transitions directly from a solid to a gas state without going through the liquid state is known as sublimation. (c) To convert a temperature from the Celsius scale to the Kelvin scale, add 273 to the given temperature. (d) The density of ice is lower than that of water. Q3. Which one of the following set of phenomena would increase on raising the temperature? (a) Diffusion, evaporation, compression of gases (b) Evaporation, compression of gases, solubility (c) Evaporation, diffusion, expansion of gases (d) Evaporation, solubility, diffusion, compression of gases Q4. The process of conversion of a solid into a gas without passing through the liquid state is called A) Evaporation B) Condensation C) Sublimation D) Fusion Q5. When water at 0°C freezes to form ice at the same temperature of 0°C, then it: (a) Absorbs some heat (b) Releases some heat (c) Neither absorbs nor releases heat 5 (d) Absorbs 3.34 x 10 J/kg of heat PRASHANT KIRAD Q6. Water as ice has a cooling effect, whereas water as steam may cause severe burns. Explain these observations. Q7. What do you understand by the term ‘latent heat of fusion’? How much is the latent heat of fusion of ice? Q8. Substance ‘A’ has high compressibility and can be easily liquefied. It can take up the shape of any container. Predict the nature of the substance. Enlist four properties of this state of matter. Q9. Liquids and gases can be compressed but it is difficult to compress solids. Why? Q10. The melting point of ice is 275 K. What does this mean? Explain in detail. Q11. When a crystal of potassium permanganate is placed in a beaker of water, its purple color spreads throughout. What does this observation conclude about potassium permanganate and water? Q12. Convert the following temperature to Celsius scale: i)The temperature is 300 K ii)The temperature is 573 K Q13. Why are we able to sip hot tea or milk faster from a saucer rather than a cup? Q14. What are the characteristics of the particles of matter? Q15. Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy, and density. 9th Phodenge! PRASHANT KIRAD SOLUTION Ans 1. B Ans 2. D Ans 3. C Ans 4. C Ans 5. B Ans6. Water turns into ice when the temperature decreases to 0°C. Water turns into steam at 100°C when heat is supplied to the water. Water as steam has more latent heat, while water as liquid does not. Hence, water as steam may cause severe burns, while water as ice has a cooling effect. Ans 7. The amount of heat that is required to change 1 kg of solid into liquid at atmospheric pressure without any change in temperature at its melting point, is known as latent heat of fusion. The latent heat of fusion of ice in SI unit is 3.35 × 10 5 J/kg. Ans 8. A’ is a gas. Properties of gases: They do not have fixed shape and fixed volume. They have large interparticle space. They have least forces of attraction between the molecules. They are highly compressible. Ans 9. Liquids and gases have intermolecular space, on applying pressure externally on them the molecules can come closer thereby minimizing the space between them. But in case of solids there is no intermolecular space to do so. Ans 10. Ice is solid at 0°C i.e., 273 K. The molecules of ice are tightly packed. These molecules have to overcome the force of attraction with which they are held and hence they gain this heat from the surrounding but the temperature remains the same as their energy is used to overcome the force of attraction between the particles. The particles have their state and starts PRASHANT KIRAD vibrating freely and a stage reaches when the solid ice melts and is converted to liquid state at the same temperature i.e., 273 K. Ans11. The purple color spreading throughout the water indicates diffusion. Potassium permanganate, being a solid, initially settles at the bottom, but water molecules collide with it and the particles intermingle due to sufficient space between the molecules in the liquid state. Ans 12. : The temperature is 300 K. K = 273 + C : C = K - 273 = 300 – 273 = 27 C The temperature is 573 K When we use: K = 273 + C C = 573 - 273 = 300 °C Ans 13. When we use a saucer instead of a cup the surface for evaporation to occur will be increased resulting in faster evaporation of particles of tea or milk and allowing it to cool faster and taking a sip becomes easier. Ans 14. The particles of matter have the following characteristics: i.The particles of matter are in continuous motion. ii. There are gaps between the particles of matter. iii.There is a force of attraction between the particles of matter which keeps them together. Ans 15. Rigidity: This is the ability of matter to keep its shape when forces are applied. Solids have rigidity. Compressibility: This is the ability to be squashed when pressure is applied. Some liquids and all gases can be compressed. Fluidity: This is the ability to flow and change shape when a force is applied. Liquids and gases exhibit fluidity. Filling a gas container: Gases can be easily compressed and fill any container they are in, which makes them cost-effective to transport PRASHANT KIRAD Shape: Solids have a definite shape, while liquids take the shape of their container, and gases have no fixed shape. Kinetic Energy: Particles in matter are always moving. Solids have the least movement and kinetic energy, while gases have the most movement and highest kinetic energy. The order is: solid < liquid < gas. Density: Density is the mass of a substance per unit volume, calculated as density = mass/volume.  Class IX “Next Year Questions” FUNDAMENTAL UNIT OF LIFE PRASHANT KIRAD PRASHANT KIRAD Q1. Which of the following statements is incorrect? (a)Cytoplasm is also known as protoplasm (b)Lysosomes are known as the suicide bags of the cell (c)Mitochondria has its own DNA (d)All of the above are incorrect Q2. Where are the essential proteins and lipids required for cell membrane, manufactured? (a)Lysosome (b)Chromosomes (c)Endoplasmic reticulum (d)Mitochondria Q3.Which structure is found in plant cells but not in animal cells? (a) Chloroplast (b) Centrioles (c) Lysosomes QQ (d) Nucleus Q4.The components of chromosomes are (a) DNA (b) protein (c) DNA, protein (d) RNA Solution Q5. Which of the following is not a function of the endoplasmic reticulum? (a) It acts as a transport channel for proteins between the nucleus, cytoplasm and the cell membrane. (b) It moves materials between different regions of the cytoplasm (c) It could be used for energy generation (d) It could be the location for biochemical activities in the cell Q6.There would be no plant life if chloroplasts did not exist. Justify. Q7.Why do the animal cells not have cell wall? PRASHANT KIRAD Q8. Do you agree “A cell is a building unit of an organism”. If yes, explain why. Q9. Write a note on Golgi apparatus and the functions it performs. Q10.In brief state what happens when: (a) dry apricots are left for sometime in pure water and later transferred to sugar solution? (b) a red blood cell is kept in concentrated saline solution? (c) the plasma membrane of a cell breaks down? (d) rheo leaves are boiled in water first and then a drop of sugar syrup is put on it? (e) golgi apparatus is removed from the cell? Q11.What is the significance of pores present on the nuclear membrane? Q12. How do substances like CO2 and water moves in and out of the cell? Discuss. Q13. How will you relate nucleus with DNA? Q14. How does an Amoeba obtain its food? Q15.Define- a) Diffusion b) Osmosis 9th Phodenge! PRASHANT KIRAD SOLUTION Ans1. a Ans2.c Ans3.a Ans4.c Ans5. c Ans 6. Chloroplasts contain the pigment chlorophyll which is responsible for food preparation in plants by the process of photosynthesis. Hence without chloroplasts, plants would not be able to perform photosynthesis and would not survive. Ans7. Animal cells lack a cell wall because it would limit their flexibility and movement. Instead, animal cells only have a flexible plasma membrane, which allows for mobility and the formation of various tissues. 5 Ans8.An organism is made up of various organ systems like digestive system, nervous system, etc. These organ systems in turn are made up of various organs which are made up of tissues. Also tissues are a group of cells performing the same function. Hence, a cell is the building unit of an organism. Cell → tissue → organ → organ system → organism Ans9.Golgi apparatus or Golgi bodies or Golgi complex is composed of membrane-bound fluid-filled vesicles, vacuoles and cisternae. In animal cells they are larger and only one or two in number, while in plants they are smaller and more in number. Also, in plant cells, they are distributed throughout – the cytoplasm and are called dictyosomes. Functions: It is involved in the transport and modification of protein, lipids as well as carbohydrates. It helps in the formation of cell plate during cell division. It is also involved in the formation of cell wall, plasma membrane lysosomes and peroxisomes. PRASHANT KIRAD The material synthesised near endoplasmic reticulum is packaged and dispatched to various targets and outside the cell through the Golgi apparatus. Ans10.(a) The apricots swell due to osmosis initially and when transferred to sugar solution shrink again due to exosmosis. (b) RBCs shrink due to exosmosis. (c) It would lead to scattering of cell organelles and there will be no functioning of the organs. (d) Boiling makes the cells non-functional, and thus they cannot undergo osmosis or any other process effectively. (e) Function of Golgi apparatus is packing, storing and transfer of protein. It would affect the functioning of cell. Ans11.The pores present on the nuclear membrane allow transport of water- soluble molecules across the nuclear envelope. RNA and ribosomes move out of the nucleus, whereas carbohydrates, lipids and proteins move into the nucleus. Ans12.The exchange of gases like CO2 and O2 in cells happens through diffusion. Diffusion is the movement of substances from a region of high concentration to a region of low concentration. Inside the cell, CO2 is produced during respiration, leading to a higher concentration of CO2 in the cell compared to outside. On the other hand, O2 is used up during respiration, reducing its concentration inside the cell, while it remains higher in the surroundings. As a result: CO2 diffuses out of the cell. O2 diffuses into the cell. This process allows gases to move in and out naturally without using energy. Ans13.Nucleus is located in the center of the cell. It is the main cell organelle and controls all the activities of cell. A membrane having pores surrounds it. Its chief compounds are chromatin material and nucleolus. Chromatin material when condenses form knot like structures called chromosomes. Chromosomes contain hereditary units called genes, which in turn are made up of DNA. These DNA are carriers of characters from one generation to another OR The nucleus controls all cell activities, including growth and reproduction. It contains chromosomes made up of DNA, which carry genetic information that is passed from one generation to another. PRASHANT KIRAD Ans 14. Amoeba takes in food by extending pseudopodia (projections of its cell membrane) around the food particle. Once the food is surrounded, it is enclosed inside the cell, forming a food vacuole. Inside the food vacuole, the food is digested with the help of enzymes. This process of engulfing food is called endocytosis (phagocytosis). Ans15.a) Diffusion - It is the spontaneous movement of molecules from a region of high concentration to lower concentration,. It is faster in the gaseous phase than in liquids and solids. b) Osmosis - It is the passage of solvent (water) from a region of higher concentration through a semi - permeable membrane to a region of lower concentration. Osmosis is a purely mechanical process by which cells absorb water without spending any amount of energy.  Class IX “Next Year Questions” MOTION PRASHANT KIRAD PRASHANT KIRAD Q1. The physical quantity that has both magnitude and direction is known as a. vectors b. scalars c. Both(a) and (b) d. Neither (a) or (b) Q2. What does the slope of the distance-time graph give? a. speed b. velocity c. acceleration d. displacement Q3. Which of the following situations is true and possible? a. If the velocity of a body is zero, then the acceleration can be non- zero b. A body moving at a constant velocity can have acceleration c. The magnitude of distance and displacement are equal in a circular motion d. All of the above Q4. What would be the displacement of a particle moving in a circular path of radius r after a displacement of half a circle? a. 2πr b. πr c. 2r d. Zero Q5. Suppose a ball is thrown vertically upwards from a position P above the ground. It rises to the highest point Q and returns to the same point P. What is the net displacement and distance travelled by the ball? PRASHANT KIRAD Q6. What is the difference between uniform velocity and non-uniform velocity? Q7. Represent a distance-time graph for uniform and non-uniform motion of an object. Q8. What do you understand by instantaneous velocity? Q9. A bus travels at a speed of 90 km/h. Brakes are applied to produce a uniform acceleration of -0.5 m/s 2. How far will the train go before it comes to rest. Q10. A truck starting from rest moves with a uniform acceleration of 5 2 m/s. Find its velocity when it has travelled a distance of 1 km. Q11. Define and classify motion. Q 12. Differentiate between distance and displacement. Q13. An object has moved through a distance. Can it have zero displacements? If yes, support your answer with an example. Q14. What can you say about the motion of an object if its speed time graph is a straight line parallel to the time axis? 2 Q15. A ball is gently dropped from a height of 20m, if its velocity increases uniformly at the rate of 10m/s with what velocity will it strike the ground? After what time will it strike the ground? 9th Phodenge! PRASHANT KIRAD SOLUTION Ans1. a Ans2.a Ans3.a Ans4.c Ans5. Displacement is zero. Distance is twice the distance between position P and Q. Ans 6. Uniform velocity: An object with uniform velocity covers equal distances in equal intervals of time in a specified direction, e.g., an object moving with speed of 40 kmh-1 towards west has uniform velocity. Non-uniform velocity: When an object covers unequal distances in equal intervals of time in a specified direction, or if the direction of motion changes, it is said to be moving with a non-uniform or variable velocity, e.g., object moving along 5 a path with varying speeds and directions. Ans7. the distance-time graph, time is taken on the x-axis and distance is taken on the y-axis. The graph depicts the distance covered by the object during a particular time interval. In uniform motion, the uniform speed of the object moving is equal to the slope of the plot, which is a straight line. The graph has a varying slope when the object is in non-uniform motion. When the distance decreases with time in non-uniform motion, the slope is decreasing in value. PRASHANT KIRAD Ans8.Instantaneous velocity is defined as the the velocity of an object under motion at a specific point of time. Measured using SI unit m/s. Ans9. Initial speed = u = 90km/h u = (90 × 1000)/60 × 60 = 90000/3600 = 25m/s a = -0.5 m/s 2 since the bus comes to rest therefore velocity, v = 0 v = u + at 0 = 25 + (-0.5) × t 0 = 25 – 0.5t 0.5t = 25 t = 25/0.5 = 50seconds s = ut + ½ at2 = 25×50 + ½ × (-0.5) × 502 s = 1250 – 625 = 625m Ans 10. Initial velocity, u = 0 Acceleration, a = 5m/s 2 Displacement, s = 1 km = 1000m According to the third equation, v 2= u 2+ 2as v = 2as v = 2×5×1000 v = 100 m/s Ans11. Motion is defined as the change in position of an object continuously concerning origin and time. We perceive an object when its position changes with time. The origin is called a fixed reference point. Motion is measured by speed, velocity and acceleration. PRASHANT KIRAD Ans 12 Ans13. Yes, if an object is moved through a distance it can have zero displacement because displacement of an object is the actual change in its position when it moves from one position to the other position. So if an object travels from point A to B and then returns back to point A again, the total displacement will be zero. Ex: an object going around a loop and returning to its starting point. Ans14. Such a graph indicates that the object is travelling with uniform velocity PRASHANT KIRAD Ans15  Class IX “Next Year Questions” Tissues PRASHANT KIRAD PRASHANT KIRAD Q1. Collenchyma cells provide flexibility to plants because they have: (a) Thick cellulose walls (b) Thin walls without intercellular spaces (c) Lignified walls (d) Unevenly thickened walls Q2. Xylem and phloem are types of: A) Epithelial tissue B) Nervous tissue C) Muscular tissue D) Plant tissues Q3. Which tissue makes up husk of coconut? (a) Parenchyma (b) Sclerenchyma (c) Collenchyma (d) Xylem Q4.Which plant tissue is primarily responsible for transporting water? (a) Xylem (b) Phloem (c) Epidermis (d) Parenchyma Q5. The tissue responsible for the movement of the body and its parts is: A) Epithelial tissue B) Nervous tissue C) Muscular tissue D) Connective tissue PRASHANT KIRAD Q6.What is the role of epidermis in plants? Q7.(a) What is the lining of blood vessels made up of? (b) What is the lining of small intestine made up of? (c) What is the lining of kidney tubules made up of? (d) Where are the epithelial cells with cilia found? Q8. Why are intercellular spaces absent in sclerenchyma tissues? Q9. Differentiate between parenchyma and collenchyma. Q10.What are the components of xylem tissue? Explain their functions. Q11.What does skeletal tissue comprise of give its functions. Q 12.Give reasons: (a) Intercellular spaces are absent in sclerenchyma tissues. (b) We get a crunchy and granular feeling when we chew pear fruit. Q13. How many types of elements are present in the phloem? Q14. If you are provided with three slides, each containing one type of muscles fibres, how will you identify them? Q15. Why are xylem and phloem called complex tissues? How are they different from one other ? 9th Phodenge! PRASHANT KIRAD SOLUTION Ans1. D Ans2.D Ans3.B Ans4.a Ans5. C Ans 6. The epidermis is the outer protective tissue of plants. It prevents water loss, protects against mechanical injury, and acts as a barrier to pathogens. Ans 7. (a) Squamous epithelium (b) Columnar epithelium (c) Cuboidal epithelium (d) Respiratory tract 5 Ans 8. Intercellular spaces are absent in sclerenchyma tissues because these cells have thick lignified walls that are tightly packed together. This absence of spaces provides mechanical strength and rigidity to the plant, making sclerenchyma ideal for supporting and protecting plant structures. Ans 9. Parenchyma Collenchyma Cells have thin walls. Cells have unevenly thickened walls. Found in all parts of the plant. Found in young stems and petioles. Provides mechanical support and Involved in storage and photosynthesis. flexibility. Cells are loosely packed with intercellular Cells are tightly packed without spaces. intercellular spaces. PRASHANT KIRAD Ans10.Xylem is composed of four types of elements: 1. Tracheids: These are elongated, tube-like cells with thick lignified walls that conduct water and provide mechanical support. 2. Vessels: These are long, continuous tubes formed by the fusion of several cells, allowing efficient water conduction. 3. Xylem Parenchyma: These cells store food and help in the lateral conduction of water. 4. Xylem Fibres: These are thick-walled, dead cells that provide mechanical strength to the plant. Ans11.Skeletal tissue comprises bone and cartilage. Functions of Skeletal Tissue: 1. Bone: Provides shape and support to the body. Protects internal organs like the brain, heart, and lungs. Serves as a site for muscle attachment and enables movement. 2. Cartilage: Provides flexibility and support at certain places like the ear, nose, and trachea. Reduces friction and absorbs shock at joints. Ans 12. (a) Sclerenchyma cells have lignified cell walls which makes them compact and leaves no intercellular spaces. (b) Pear has sclerenchyma stone cells which are granular in texture. Hence, we get the crunchy and granular feeling while chewing a pear. Ans13.There are four types of elements are present in the phloem they are: Sieve tube: Helps in conduction of food material Companion cells: It helps sieve tube in conduction of food material Phloem parenchyma: storage Phloem fibres: It provides mechanical support. Ans14.a) Skeletal muscles or voluntary muscles show alternate light and dark bands under microscope b) Unstriated muscles or involuntary muscles show no light or dark bands, they are uninucleate. c) Cardiac muscles fibres show light and dark bands, fibres are interconnected with one or two nuclei. PRASHANT KIRAD Ans15.Xylem and phloem are called complex tissues because they consist of more than one type of cells that work together to perform a common function. Xylem Phloem Primarily composed of dead cells (except Primarily composed of living cells xylem parenchyma). (except phloem fibres). Transports water and minerals from Transports food from leaves to other roots to aerial parts of the plant. parts of the plant. Movement is unidirectional (only Movement is bidirectional (up and upwards). down). Components include sieve tubes, Components include tracheids, vessels, companion cells, phloem parenchyma, xylem parenchyma, and xylem fibres. and phloem fibres.  Class IX “Next Year Questions” Force and Law of Motion PRASHANT KIRAD PRASHANT KIRAD Q1. A truck of mass 2000 kg is moving with a velocity of 30 m/s. What is its momentum? a) 600 kg m/s b) 60,000 kg m/s c) 6000 kg m/s d) 6,000,000 kg m/s Q2. A body of mass 2 kg is moving with a velocity of 10 m/s. It is stopped by applying a force of 5 N. How much time will it take to stop the body? a) 1 s b) 2 s c) 3 s d) 4 s Q3. If the momentum of an object is doubled, its kinetic energy becomes: a) Half b) Double c) Four times d) Remains the same Q4. When a force of 1 N is applied on a body of mass 1 kg, the acceleration produced is: a) 1 m/s² b) 10 m/s² c) 0.1 m/s² d) 100 m/s² Q5. When a force of 10 N is applied to an object weighing 2 kg, what would be the resultant acceleration of the object? a) 20 m/s² b) 5 m/s² c) 2 m/s² d) 0.2 m/s² PRASHANT KIRAD Q6. If action is always equal to the reaction, explain how a horse can pull a cart? Q7.A body of mass 10 kg is moving with a velocity of 5 m/s. Calculate its momentum. Q8.If you hit a carpet with a stick, dust comes out. Explain. Q9. A motor vehicle has a mass of 1500 kg. How large must the force between the car and the road be for the car to stop with a negative acceleration of 1.7 m/s² Q10. A body with a mass of 100 kg is accelerated uniformly from a speed of 5 m/s to 8 m/s in 6 s. Calculate the starting and ending moments of the object. Also, find the magnitude of the force being exerted on the object. Q 11. Two people manage to push a car with a mass of 1200 kg at a constant speed on a flat road. Three people can push the same car to produce an acceleration of 0.2 m/s². With what force does each person push the car? (Assume that all people push the car with the same physical force) Q12. What is the acceleration produced by a force of 12 newton exerted on an object of mass 3 kg? Q13. How many types of inertia do the material bodies have? Q14. Two identical bullets are fired one by a light rifle and another by a heavy rifle with the same force. Which rifle will hurt the shoulder more and why? Q15.Plot a graph between force applied on a body and the acceleration produced in the given mass, assuming that the magnitude of force is constantly changing. 9th Phodenge! PRASHANT KIRAD SOLUTION Ans1. b Ans2.b Ans3.c Ans4.a Ans5. b Ans 6.The horse pushes backward on the ground with its hooves. According to Newton's Third Law, the ground exerts an equal and opposite reaction force forward on the horse. This forward force allows the horse to move and pull the cart. Ans7. Momentum p=mv m=10kg,v=5m/s p=10×5=50 kg⋅m/s Ans8.When a certain rug is struck with a stick, the stick exerts a force on the rug that sets it in motion. The inertia of the dust particles in the mat counteracts the change in the movement of the mat. Therefore, the forward movement of the mat exerts a backward force on the dust particles, setting them in motion in the opposite direction. That will help the dust come out of the mat when hit.. Ans9. Suppose vehicle mass (m) = 1500 kg acceleration (a) = -1.7 m/s² By the second law of motion, F = ma F = 1500 kg × (-1.7 ms -²) = -2550 N So the force acting between the car and the road is -2550 N, acting in the opposite direction from the direction of the car’s motion. PRASHANT KIRAD Ans 10.Assume mass of object (m) = 100 kg initial velocity (u) = 5 m/s final velocity (v) = 8 m/s duration (t) = 6 s also amount of initial motion (m × u) = 100 kg × 5 m/s = 500 kg.m/s final momentum (m × v) = 100 kg × 8 m/s = 800 kg.m/s acceleration of the object (a) = (v-u)/t = (8-5)/6m/s² hence the object accelerates at 0.5 m/s². This shows that the force (F = ma) acting on the object will be: F = (100 kg) × (0.5 m/s²) = 50 N Therefore the force of 50 N on the object will be 100 kg applied, accelerating in 0.5 m/s² Ans11.Given The mass of the car (m) = 1200 kg If a third person starts to push the car, the acceleration (a ). is 0.2m/s². Hence, the force applied by the third person is (F = ma): F = 1200 kg × 0.2 m/s² = 240 N The force applied by the third person on the car is 240 N. Since the three people apply the same physical energy, the force exerted by each person on the car is 240/3 = 80N. Ans12.In this problem, force, F = 12 N Mass, m = 3 kg We know that F = m × a, Putting the given values, we have 12 = 3 × a a = 12/3 or, Acceleration, a = 4 m/s² Ans13.All material bodies can have three types of inertia. (i) Inertia of rest - A body at rest does not change its state of rest unless a force is applied on it. (ii) Inertia of motion - A moving body remains in motion unless acted upon by an external force." (iii) Inertia of direction - A body resists any change in its direction of motion unless acted upon by an external force PRASHANT KIRAD Ans14. The light rifle will hurt the shoulder more because, due to its lower mass, it experiences a greater recoil (backward acceleration) when the bullet is fired. This happens because of Newton's Third Law of Motion: the force exerted by the bullet forward causes an equal and opposite force backward on the rifle. Since the light rifle has less mass, it accelerates more, producing greater recoil force, which impacts the shoulder more. Ans15.  Class IX “Next Year Questions” ATOMS AND MOLECULES PRASHANT KIRAD PRASHANT KIRAD Q1.How many moles are present in 40 g of He? (a) 5 moles (b) 20 moles (c) 6 moles (d) 10 moles Q2. What is the chemical formula of sodium carbonate? (a) Na₂CO₃ (b) NaHCO₃ (c) NaCO₃ (d) Na₂HCO₃ Q3. The atomicity of K₂Cr₂O₇ is (a) 9 (b) 11 (c) 10 (d) 2 Q4.Atomicity of Chlorine and Argon is (a) Diatomic and Monoatomic (b) Monoatomic and Diatomic (c) Monoatomic and Monoatomic (d) Diatomic and Diatomic Q5.Symbol of Iron is – (a) Ir (b) I (c) Fe (d) None of these Q6. State the Postulates of Dalton Theory? Q7. State the number of atoms present in each of the following chemical species (a) CO₃²⁻ (b) PO₄³⁻ (c) P₂O₅ PRASHANT KIRAD (d) CO 24 Q8.A sample of vitamin C is known to contain 2.58 x10 oxygen atoms. How many moles of oxygen atoms are present in the sample? Q9.Which is the mass of: (a) 0.2 mole oxygen molecules? (b) 0.5 mole of water molecules? Q10. Explain why the number of atoms in one mole of hydrogen gas is double the number of atoms in one mote of Helium gas? Q11.What is the mass of: (a) 1 mole of nitrogen atoms ? (b) 4 moles of aluminium atoms (Atomic mass of aluminium = 27) ? (c) 10 moles of sodium sulphite (Na₂SO₃) ? Q 12. (a) Define: (i) Molecular mass, (ii) Avogadro constant. (b) Calculate the number of molecules in 50 g of CaCO₃. (Atomic mass of Ca = 40 u, C = 12 u and O = 16 u) (c) If one mole of sodium atom weighs 23 g, what is the mass (in g) of one atom of sodium. Q13.The relative atomic mass of oxygen atom is 16. Explain its meaning. Q14.Write the molecular formulae for the following compounds (a) Copper (I) bromide (b) Aluminium (III) nitrate (c) Calcium (II) phosphate (d) Iron (III) sulphide (e) Mercury (I) chloride Q15.Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g. The molar atomic mass of magnesium is 24g mol. 9th Phodenge! PRASHANT KIRAD SOLUTION Ans1. d Ans2.a Ans3.b Ans4.a Ans5. c Ans 6. Dalton’s atomic theory states that all matter, be it an element, a compound, or a mixture is composed of small particles called atoms. The postulates of the theory are: (i) All matter is made of very tiny particles called atoms, which participate in chemical reactions. (ii) Atoms are indivisible particles, which cannot be created or destroyed in a chemical reaction. (iii) Atoms of a given element are identical in mass and chemical properties. (iv) Atoms of different elements have different masses and chemical properties. (v) Atoms combine in the ratio of small whole numbers to form compounds. (vi) The relative number and kinds of atoms are constant in a given compound. Ans7. (a) There are four atoms in CO₃²⁻. (b) There are five atoms in PO₄³⁻. (c) There are seven atoms in P₂O₅. (d) There are two atoms in CO. Ans8. 24 The number of oxygen atoms in the given sample = 2.58 X 10 23 We know that 1 mole contains 6.022 X 10 oxygen atoms So, 24 23 2.58 X 1024 oxygen atoms = 2.58 X 10 / 6.022 X 10 2.58 X 1024 oxygen atoms = 4.28 moles. PRASHANT KIRAD Ans9. The mass is as follows: (a) Mass of 1 mole of oxygen atoms = Mass=0.2 × 32 = 6.4g (b) A mole of water molecules mass is 18u, weighing 18g. 0.5 moles of water molecules equals Mass=0.5 × 18 = 9 g Ans10.One mole of hydrogen gas has twice as many atoms as one mole of helium gas due to the fact that hydrogen molecules are diatomic—that is, they are made up of two hydrogen atoms—while helium molecules are monoatomic. Ans11. (a) 1 mole of nitrogen atoms = 1 × Gram atomic mass of nitrogen atom = 1 × 14 g = 14 g (b) 4 moles of aluminium atoms = 4 × Gram atomic mass of aluminium atoms = 4 × 27 g = 108 g (c) Mass of 10 moles of sodium sulphite (Na₂SO₃): = 10 × (2 × Gram atomic mass of Na + 1 × Gram atomic mass of S + 3 × Gram atomic mass of O) = 10 × (2 × 23 g + 1 × 32 g + 3 × 16 g) = 10 × (46 g + 32 g + 48 g) = 10 × 126 g = 1260 g Ans12. a. (i) Molecular Mass Molecular mass (or molecular weight) is defined as the mass of a molecule of a substance. It is calculated as the sum of the atomic masses of all the atoms in the molecule, expressed in atomic mass units (u). (ii)The Avogadro constant is the number of particles (atoms, molecules, or ions) in one mole of a substance. Its value is approximately 6.022 × 10²³ particles per mole. (b) Calculation: Number of molecules in 50 g of CaCO₃ Molecular mass of CaCO₃: Molecular mass = (Ca) + (C) + 3 × (O) = 40 + 12 + 3 × 16 = 100 u Moles of CaCO₃ in 50 g: Moles = Mass / Molar Mass = 50 / 100 = 0.5 mol Number of molecules: Using Avogadro constant (Nₐ = 6.022 × 10²³): Number of molecules = Moles × Nₐ = 0.5 × 6.022 × 10²³ = 3.011 × 10²³ molecules PRASHANT KIRAD (c) Mass of one atom of sodium Mass of one mole of sodium: Given, mass of 1 mole = 23 g. Number of atoms in one mole of sodium: Nₐ = 6.022 × 10²³ atoms/mol Mass of one atom: Mass of one atom = Mass of one mole / Nₐ = 23 / 6.022 × 10²³ = 3.82 × 10⁻²³ g Ans13:The relative atomic mass of an atom is the average mass of the atom, as compared to 1\12th the mass of one carbon-12 atom. Ans14: (a) The molecular formula of Copper (I) bromide is CuBr. (b) The molecular formula of Aluminium (III) nitrate is Al(NO₃)₃. (c) The molecular formula of Calcium (II) phosphate is Ca₃(PO₄)₂. (d) The molecular formula of Iron (III) sulphide is Fe₂S₃. (e) The molecular formula of Mercury (I) chloride is Hg₂Cl₂. Ans15. Mass of magnesium ribbon = 12 g Molar mass of magnesium = 24 g Number of moles = Mass / Molar Mass Number of moles = 12 / 24 Number of moles = 0.5 moles. Hence, there are half moles of magnesium in a 12 g magnesium ribbon.