Class 9 Practice Level 3 – Set 2 – Matter in Our Surrounding Leave a Comment / By Gulam Hamza / August 26, 2024 Class 9 Practice Level 3 – Set 2 – Matter in Our Surrounding Total questions: 15 1. Plasma differs from gas in that it: Topic: Plasma State Has a definite shape Has charged particles Is less compressible Is a good conductor of electricity None 2. Which of the following is not a physical change? Topic: Physical Changes Melting of ice Boiling of water Rusting of iron Sublimation of iodine None 3. When a gas turns into a liquid, the process is called: Topic: Condensation Evaporation Condensation Freezing Sublimation None 4. Boiling point of a liquid varies with: Topic: Boiling Point Temperature Humidity Pressure Volume None 5. Which of the following processes requires the absorption of heat? Topic: Temperature and Heat Freezing Condensation Evaporation Deposition None 6. Why does sublimation occur in certain substances like dry ice? Topic: Sublimation Sublimation occurs because these substances have weak intermolecular forces that allow them to change directly from solid to gas without passing through the liquid state. Sublimation occurs because these substances have strong intermolecular forces that make the transition from solid to liquid very difficult. Sublimation occurs because these substances have a low melting point and high boiling point. Sublimation occurs because these substances are highly reactive. None 7. How does increasing atmospheric pressure affect the boiling point of a liquid? Topic: Effect of Pressure on Boiling Point It increases the boiling point because more energy is required for the liquid molecules to escape into the vapor phase. It decreases the boiling point because the molecules escape more easily into the vapor phase It has no effect on the boiling point. It causes the liquid to boil at a lower temperature because the molecules gain more energy. None 8. Why does water expand when it freezes, unlike most other substances? Topic: Anomalous Expansion of Water Water expands upon freezing because the hydrogen bonds in ice form a crystalline structure that occupies more space than in liquid water Water expands upon freezing because its molecules move closer together. Water expands upon freezing because of the increase in kinetic energy. Water expands upon freezing because of the decrease in atmospheric pressure. None 9. Why does water have a high latent heat of vaporization? Topic: Latent Heat of Vaporization Because water molecules are strongly attracted to each other, requiring more energy to separate them Because water molecules are weakly attracted to each other, requiring less energy to separate them Because water molecules have a low boiling point. Because water molecules have a low specific heat capacity. None 10. What is the significance of the critical temperature in the behaviour of gases? Topic: Critical Temperature and Pressure The critical temperature is the highest temperature at which a substance can exist as a liquid, regardless of the pressure applied. The critical temperature is the lowest temperature at which a gas can exist without condensing into a liquid. The critical temperature is the temperature at which a solid changes directly into a gas. The critical temperature is the temperature at which a liquid changes directly into a solid. None 11. What causes surface tension in liquids, and why is it important? Topic: Surface Tension Surface tension is caused by the cohesive forces between liquid molecules, which create a "skin" on the surface that allows insects to walk on water Surface tension is caused by the adhesive forces between liquid molecules and the container walls, which prevent the liquid from spreading. Surface tension is caused by the pressure difference between the top and bottom of the liquid surface, which pulls the molecules together. Surface tension is caused by the repulsion between liquid molecules, which creates a barrier on the surface. None 12. Why does diffusion occur more rapidly in gases than in liquids? Topic: Diffusion Rate in Gases Diffusion occurs more rapidly in gases because gas particles move faster and are farther apart, allowing them to spread out more quickly. Diffusion occurs more rapidly in gases because gas particles are closer together and move more slowly. Diffusion occurs more rapidly in gases because gas particles are heavier. Diffusion occurs more rapidly in gases because gas particles are smaller. None 13. What is the triple point of a substance in a phase diagram? Topic: Diffusion Rate in Gases The triple point is the temperature and pressure at which solid, liquid, and gas phases coexist in equilibrium. The triple point is the temperature and pressure at which a substance changes directly from solid to gas. The triple point is the temperature and pressure at which a substance changes from liquid to gas. The triple point is the temperature and pressure at which a substance changes from solid to liquid. None 14. Which of the following factors will decrease the rate of evaporation? Topic: Factors Affecting Evaporation Decreasing the temperature Increasing the temperature Increasing the surface area Decreasing the humidity None 15. Why does the boiling point of a solvent increase when a non-volatile solute is added? Topic: Boiling Point Elevation Because the addition of a non-volatile solute lowers the vapor pressure of the solvent, requiring more heat to reach the boiling point. Because the addition of a non-volatile solute raises the vapor pressure of the solvent, allowing it to boil at a lower temperature. Because the addition of a non-volatile solute decreases the kinetic energy of the solvent molecules. Because the addition of a non-volatile solute increases the volume of the solvent. None 1 out of 15 Time's up
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