Mark Questions (Very Short Answer)
Q16. Which gas is supplied in liquefied form at home and in hospitals?
Q23. Describe the factors affecting evaporation.
Ans.: Temperature: Higher temperature increases evaporation.
Surface Area: More surface area leads to faster evaporation.
Humidity: Lower humidity increases evaporation.
Q24. Why do we wear cotton clothes in summer?
Ans.: Cotton absorbs sweat and allows easy evaporation, keeping the body cool.
Q25. Why do we feel cold when we put acetone or ether on our palm?
Ans.: They evaporate quickly, absorbing heat from our skin.
Q26. Write three characteristics of particles of matter and give an example.
Ans.: Particles have spaces between them (Example: Sugar dissolving in water).
Particles are in constant motion (Example: Diffusion of perfume).
Particles attract each other (Example: Iron nails sticking together).
Q27. Write the characteristic responsible for:
Ans.: Smell of perfume spreading in the room: Diffusion.
Water taking the shape of the container: Fluidity.
Q28. Name three states of matter, give one example of each, and state three characteristic properties of each.
Ans.: Solid: Example: Ice, has definite shape, volume, and high density.
Liquid: Example: Water, has definite volume but no definite shape.
Gas: Example: Oxygen, no definite shape or volume.
Q29. What is evaporation? How can it be made faster?
Ans.: Evaporation is the process where liquid turns into gas below its boiling point.
Can be increased by increasing temperature, surface area, and airflow.
Q30. Draw the ‘states of matter triangle’ to show the interconversion of states of matter.
Ans.: (Diagram-based question; should show the transitions between solid, liquid, and gas).
Q31. Why does a desert cooler cool better on a hot, dry day?
Ans.: Evaporation is faster due to high temperature and low humidity.
Q32. Compare the properties of solids, liquids, and gases in tabular form.
Q1. Write the three states of matter.
Ans.: Solid, Liquid, and Gas.
Ans.: Solid, Liquid, and Gas.
Q2. Which has more density – liquid or solid?
Ans." Solid has more density than liquid.
Ans." Solid has more density than liquid.
Q3. What is the melting point of ice?
Ans.: 0°C or 273 K.
Q4. Convert the boiling point of alcohol (78°C) into Kelvin scale.
Ans.: 78 + 273 = 351 K.
Q5. Why do gases exert pressure?
Ans.: Due to the continuous and random motion of gas particles.
Q6. How do we liquefy gases?
Ans.: By applying pressure and reducing temperature.
Q7. What happens to particles when salt dissolves in water?
Ans.: They get uniformly distributed in water.
Q8. What is the physical state of water at:
Ans.: 0°C: Solid (Ice)
25°C: Liquid (Water)
Ans.: 0°C or 273 K.
Q4. Convert the boiling point of alcohol (78°C) into Kelvin scale.
Ans.: 78 + 273 = 351 K.
Q5. Why do gases exert pressure?
Ans.: Due to the continuous and random motion of gas particles.
Q6. How do we liquefy gases?
Ans.: By applying pressure and reducing temperature.
Q7. What happens to particles when salt dissolves in water?
Ans.: They get uniformly distributed in water.
Q8. What is the physical state of water at:
Ans.: 0°C: Solid (Ice)
25°C: Liquid (Water)
Q9. What is the chemical name of dry ice?
Ans.: Solid Carbon Dioxide (CO₂).
Q10. Why is heat energy needed to melt a solid?
Ans.: To overcome the strong intermolecular forces and convert into liquid.
Q11. Convert the temperature into Celsius scale:
Ans.: 293 K = 293 - 273 = 20°C
470 K = 470 - 273 = 197°C
Mark Questions (Short Answer)
Q12. Classify matter on the basis of physical characteristics.
Ans.: Solid: Definite shape and volume.
Liquid: Definite volume but no definite shape.
Gas: Neither definite shape nor volume.
Q13. Why is solid carbon dioxide called ‘dry ice’?
Ans.: It directly converts into gas without melting (sublimation).
Q14. Why do we keep ether and acetone at cool places?
Ans.: They evaporate quickly and are highly volatile.
Q15. Write two factors that increase the rate of evaporation.
Ans.: Increase in temperature. Increase in surface area.
Ans.: Solid Carbon Dioxide (CO₂).
Q10. Why is heat energy needed to melt a solid?
Ans.: To overcome the strong intermolecular forces and convert into liquid.
Q11. Convert the temperature into Celsius scale:
Ans.: 293 K = 293 - 273 = 20°C
470 K = 470 - 273 = 197°C
Mark Questions (Short Answer)
Q12. Classify matter on the basis of physical characteristics.
Ans.: Solid: Definite shape and volume.
Liquid: Definite volume but no definite shape.
Gas: Neither definite shape nor volume.
Q13. Why is solid carbon dioxide called ‘dry ice’?
Ans.: It directly converts into gas without melting (sublimation).
Q14. Why do we keep ether and acetone at cool places?
Ans.: They evaporate quickly and are highly volatile.
Q15. Write two factors that increase the rate of evaporation.
Ans.: Increase in temperature. Increase in surface area.
Q16. Which gas is supplied in liquefied form at home and in hospitals?
Ans.: Home: LPG (Liquefied Petroleum Gas). Hospitals: Oxygen (O₂).
Q17. Compare the force of attraction between iron, rubber band, and chalk.
Ans.: Iron: Strongest force of attraction.
Chalk: Moderate force of attraction.
Rubber band: Weakest force of attraction.
Q18. Arrange sugar, water, and oxygen in increasing order of force of attraction.
Ans.: Oxygen < Water < Sugar.
Q19. Define boiling point, melting point, and evaporation
Ans.: Boiling point: Temperature at which a liquid changes into gas.
Melting point: Temperature at which a solid changes into liquid.
Evaporation: The process of liquid turning into vapor below its boiling point.
20. What is sublimation? Name two substances that undergo sublimation.
Ans.: Direct conversion of solid into gas without becoming liquid.
Examples: Naphthalene, Camphor.
Q21. Why does steam cause more severe burns than boiling water?
Ans.: Steam has more latent heat than boiling water.
Q22. Write full forms of:
Ans.: LPG: Liquefied Petroleum Gas.
CNG: Compressed Natural Gas.
Mark Questions (Long Answer)
Ans.: Iron: Strongest force of attraction.
Chalk: Moderate force of attraction.
Rubber band: Weakest force of attraction.
Q18. Arrange sugar, water, and oxygen in increasing order of force of attraction.
Ans.: Oxygen < Water < Sugar.
Q19. Define boiling point, melting point, and evaporation
Ans.: Boiling point: Temperature at which a liquid changes into gas.
Melting point: Temperature at which a solid changes into liquid.
Evaporation: The process of liquid turning into vapor below its boiling point.
20. What is sublimation? Name two substances that undergo sublimation.
Ans.: Direct conversion of solid into gas without becoming liquid.
Examples: Naphthalene, Camphor.
Q21. Why does steam cause more severe burns than boiling water?
Ans.: Steam has more latent heat than boiling water.
Q22. Write full forms of:
Ans.: LPG: Liquefied Petroleum Gas.
CNG: Compressed Natural Gas.
Mark Questions (Long Answer)
Q23. Describe the factors affecting evaporation.
Ans.: Temperature: Higher temperature increases evaporation.
Surface Area: More surface area leads to faster evaporation.
Humidity: Lower humidity increases evaporation.
Q24. Why do we wear cotton clothes in summer?
Ans.: Cotton absorbs sweat and allows easy evaporation, keeping the body cool.
Q25. Why do we feel cold when we put acetone or ether on our palm?
Ans.: They evaporate quickly, absorbing heat from our skin.
Q26. Write three characteristics of particles of matter and give an example.
Ans.: Particles have spaces between them (Example: Sugar dissolving in water).
Particles are in constant motion (Example: Diffusion of perfume).
Particles attract each other (Example: Iron nails sticking together).
Q27. Write the characteristic responsible for:
Ans.: Smell of perfume spreading in the room: Diffusion.
Water taking the shape of the container: Fluidity.
Q28. Name three states of matter, give one example of each, and state three characteristic properties of each.
Ans.: Solid: Example: Ice, has definite shape, volume, and high density.
Liquid: Example: Water, has definite volume but no definite shape.
Gas: Example: Oxygen, no definite shape or volume.
Q29. What is evaporation? How can it be made faster?
Ans.: Evaporation is the process where liquid turns into gas below its boiling point.
Can be increased by increasing temperature, surface area, and airflow.
Q30. Draw the ‘states of matter triangle’ to show the interconversion of states of matter.
Ans.: (Diagram-based question; should show the transitions between solid, liquid, and gas).
Q31. Why does a desert cooler cool better on a hot, dry day?
Ans.: Evaporation is faster due to high temperature and low humidity.
Q32. Compare the properties of solids, liquids, and gases in tabular form.
