🌡️ Chapter 2: States of Matter – Chemistry Class 10 (SOLVED MCQs)
1. What Happens to Internal Energy During Melting?
- a) It decreases
- b) It stays the same
- ✅ c) It increases
- d) It fluctuates
Explanation: During melting, the particles gain energy to overcome intermolecular forces, causing a rise in internal energy.
2. What Process Turns a Solid Directly Into a Gas?
- a) Melting
- b) Freezing
- ✅ c) Sublimation
- d) Condensation
Example: Naphthalene balls and dry ice undergo sublimation.
3. When Does Boiling Occur?
- a) Any temperature
- ✅ b) A fixed temperature
- c) Only at room temperature
- d) Any pressure
Key Point: For water, this temperature is 100°C at standard atmospheric pressure.
4. What Happens to Gas Particles During Condensation?
- a) Gain energy and move faster
- ✅ b) Lose energy and move slower
- c) Gain energy and move slower
- d) Lose energy and move faster
Science Behind It: As particles lose energy, they move closer together and slow down.
5. Which Law Relates Gas Volume and Temperature?
- a) Boyle’s Law
- ✅ b) Charles’s Law
- c) Avogadro’s Law
- d) Dalton’s Law
Remember: Charles’s Law = Volume ∝ Temperature (at constant pressure)
6. How Is Evaporation Different From Boiling?
- ✅ a) Evaporation occurs at the surface of a liquid at any temperature
- b) Boiling occurs only at the surface
- c) Evaporation requires a fixed temperature
- d) Boiling occurs at any temperature
Tip: Evaporation is a slow, surface-level process.
7. What Causes Gas Pressure to Rise According to Kinetic Theory?
- a) The volume increases
- b) The temperature decreases
- c) The number of particles decreases
- ✅ d) The temperature increases
Fact: As temperature rises, gas particles move faster and collide more frequently, increasing pressure.
8. Which Factors Affect Gas Diffusion Rate?
- a) Molecular mass
- b) Temperature
- ✅ c) Both a and b
- d) Neither a nor b
Insight: Lighter gases diffuse faster; higher temperatures speed up all diffusion.
9. What Process Do Solid Air Fresheners Use?
- a) Condensation
- b) Deposition
- ✅ c) Sublimation
- d) Freezing
Real Life: Air freshener cakes shrink over time due to sublimation.
10. Why Is Medicine Diffusion in the Body Important?
- a) It controls the temperature of the medicine
- ✅ b) It ensures the medicine reaches all parts of the body
- c) It keeps the medicine in one place
- d) It increases the molecular mass of the medicine
Takeaway: Proper diffusion ensures effective treatment throughout the body.
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