Grade 10 Chemistry Notes – Chapter 2 Matter

Chemistry Notes – Grade 10

National Curriculum Pakistan - NCP

Chapter 2: Matter

Aligned with National Curriculum Pakistan (Federal Board, NBF, PTB)

1. What is phase transition?
   A phase transition is the change of matter from one state to another, such as solid to liquid, liquid to gas, or solid directly to gas.
2. What is kinetic particle theory?
   Kinetic Particle Theory explains phase transitions through changes in internal energy. Temperature remains constant, but potential energy changes significantly, affecting inter-particle forces.
3. What happens when solid melts?
   The solid becomes a liquid. Particles gain enough energy to overcome attraction and move freely.
4. What happens when liquid boils?
   It turns into gas. Particles gain energy, move faster, and break free into gas phase at constant boiling temperature.
5. What is freezing?
   Freezing is the transition of liquid into solid as temperature drops below freezing point.
6. What happens when liquid freezes?
   Particles lose energy, slow down, and form an orderly solid arrangement.
7. What is condensation?
   Condensation is the conversion of vapor into liquid, opposite of evaporation.
8. What happens when a gas condenses?
   Particles lose energy, move closer, and form a liquid.
9. What is the process of sublimation?
   Sublimation is when a solid turns directly into gas without becoming liquid.
10. What happens to potential energy during sublimation?
    Potential energy increases significantly, allowing particles to overcome solid structure forces.
11. What happens to kinetic and potential energy when temperature changes?
    Kinetic and potential energy increase with rising temperature. Kinetic energy drops when temperature decreases.
12. What happens to potential energy during phase changes?
    Only potential energy changes; temperature remains constant.
13. What is evaporation?
    Evaporation occurs when surface molecules of a liquid gain enough energy to become vapor.
14. Where do molecules evaporate from?
    From the surface of a liquid.
15. How does evaporation cool the surroundings?
    High-energy molecules escape, lowering average energy and causing cooling.
16. Give examples of evaporation.
    Drying clothes, water from lakes, sweat from skin.
17. What is boiling?
    Boiling is when vapor forms throughout a liquid, not just the surface.
18. What forms during boiling?
    Vapor bubbles that rise and burst, releasing gas.
19. At what temperature does water boil at sea level?
    100°C (212°F).
20. Why does boiling need continuous heating?
    To maintain temperature and sustain phase change.
21. How does external pressure affect boiling point?
    Higher pressure raises, lower pressure reduces the boiling point.
22. What is the effect of lower pressure on evaporation?
    Evaporation increases as molecules escape more easily.
23. What is the effect of lower pressure on boiling?
    Liquids boil at lower temperatures under reduced pressure.
24. How does higher pressure affect evaporation?
    Evaporation decreases as it becomes harder for molecules to escape.
25. How does higher pressure affect boiling?
    Boiling point increases; more heat is needed.
26. Give an example of high-pressure effect in daily life.
    Pressure cookers cook food faster due to higher boiling point.
27. What are the four variables that define the state of a gas?
    Number of moles (n), volume (V), pressure (P), temperature (T).
28. What does Boyle’s Law state and how is it explained by kinetic theory?
    Volume is inversely proportional to pressure. Less volume means more particle collisions, increasing pressure.
29. How does Charles’s Law describe the effect of temperature on gas volume?
    Volume increases with temperature as particles move faster and occupy more space.
30. What does Avogadro’s Law tell us about gas volume and number of particles?
    Volume is directly proportional to moles. More particles require more space to keep pressure constant.
31. What is diffusion and give a real-life example?
    Movement from high to low concentration. E.g., perfume spreading in a room.
32. How does kinetic particle theory explain diffusion?
    Particles move randomly and collide, mixing evenly until equilibrium.
33. How does Graham’s law relate molecular mass to diffusion rate?
    Lighter molecules diffuse faster due to higher velocity at same kinetic energy.
34. How does temperature affect the rate of diffusion?
    Higher temperature increases particle speed and diffusion rate.
35. Why does perfume feel cold when applied to the skin?
    Evaporation absorbs heat from skin, causing a cooling sensation.
36. Why does sweating cool the body?
    Sweat evaporates using body heat, lowering temperature.
37. What is sublimation and how is it explained by kinetic theory?
    Direct change from solid to gas. Particles gain energy and escape the solid phase.
38. What types of substances undergo sublimation?
    Dry ice, camphor, and naphthalene due to weak forces.
39. How is the speed of molecules related to temperature in sublimation?
    Higher temperature increases speed and energy, enabling sublimation.
40. How is sublimation used in car and home air fresheners?
    Solids transform to vapor, releasing fragrance.
41. What role does sublimation play in 3D printing?
    Used in dye sublimation to embed ink into materials like T-shirts.
42. How is sublimation used in food preservation?
    Freeze-drying removes moisture via sublimation, extending shelf life.
43. Give some examples of deposition in daily life.
    Snow formation, soot deposits, dry ice from CO₂ gas.
44. Why is diffusion important in medicine?
    Helps drugs move from application site to target tissues.
45. How does diffusion rate affect how quickly a drug works?
    Faster diffusion leads to quicker therapeutic effect.
46. What factors affect the diffusion rate of drugs?
    Concentration gradient, drug form, and release mechanism.
47. Why do liquid drugs diffuse faster than solid ones?
    Liquid particles are already dispersed and move easily.
48. What is the purpose of controlled-release drug formulations?
    They regulate drug diffusion for consistent, long-lasting effects.

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