Thermal properties of matter explain how substances respond to changes in temperature. This chapter covers heat, temperature, thermal expansion of solids, liquids, and gases, specific heat capacity, thermal conductivity, change of state, and latent heat. These concepts are vital for understanding everyday phenomena such as boiling, melting, and heat transfer. The MCQs below will help students test their knowledge of these topics.
1. Which quantity measures the average kinetic energy of particles?
- A. Temperature ✅
- B. Heat
- C. Pressure
- D. Density
Explanation: Temperature is proportional to the average kinetic energy of the particles of a substance.
2. The SI unit of heat is:
- A. Joule ✅
- B. Calorie
- C. Watt
- D. Kelvin
Explanation: Heat is a form of energy, and its SI unit is the joule (J).
3. Which device is used to measure temperature?
- A. Thermometer ✅
- B. Barometer
- C. Hygrometer
- D. Manometer
Explanation: Thermometers measure the temperature of solids, liquids, and gases.
4. Linear expansion occurs in:
- A. Solids ✅
- B. Liquids
- C. Gases
- D. Plasmas
Explanation: Solids expand in length when heated, known as linear expansion.
5. The SI unit of specific heat capacity is:
- A. J/(kg·K) ✅
- B. J/kg
- C. J/K
- D. W/m·K
Explanation: Specific heat capacity is measured in joules per kilogram per kelvin.
6. Which property determines how quickly a material conducts heat?
- A. Thermal conductivity ✅
- B. Specific heat capacity
- C. Latent heat
- D. Elasticity
Explanation: Thermal conductivity is a measure of a material’s ability to transfer heat.
7. During melting, the temperature of a substance:
- A. Remains constant ✅
- B. Increases
- C. Decreases
- D. Changes irregularly
Explanation: During a change of state, heat energy changes the arrangement of molecules, not the temperature.
8. The heat required to change the state without temperature change is called:
- A. Latent heat ✅
- B. Specific heat
- C. Thermal expansion
- D. Heat capacity
Explanation: Latent heat is absorbed or released during a change of state without a temperature change.
9. Which metal is commonly used in cooking utensils due to high thermal conductivity?
- A. Aluminium ✅
- B. Lead
- C. Mercury
- D. Zinc
Explanation: Aluminium is lightweight and a good conductor of heat.
10. Expansion of liquids is measured using:
- A. Volumetric expansion ✅
- B. Linear expansion
- C. Areal expansion
- D. Surface expansion
Explanation: Liquids expand in volume when heated, measured as volumetric expansion.
11. Which gas law explains the expansion of gases when heated?
- A. Charles’s law ✅
- B. Boyle’s law
- C. Pascal’s law
- D. Hooke’s law
Explanation: Charles’s law states that the volume of a gas increases with temperature at constant pressure.
12. The boiling point of water decreases when:
- A. Atmospheric pressure decreases ✅
- B. Atmospheric pressure increases
- C. Temperature increases
- D. Volume decreases
Explanation: Lower atmospheric pressure reduces the temperature at which water boils.
13. Which phase change releases latent heat?
- A. Freezing ✅
- B. Melting
- C. Evaporation
- D. Sublimation
Explanation: Freezing releases latent heat as the substance changes from liquid to solid.
14. The high specific heat capacity of water makes it useful for:
- A. Cooling systems ✅
- B. Electrical circuits
- C. Fuel storage
- D. Optical lenses
Explanation: Water can absorb and store large amounts of heat without a large temperature rise.
15. Which type of expansion is considered in railway track gaps?
- A. Linear expansion ✅
- B. Volumetric expansion
- C. Areal expansion
- D. Thermal contraction
Explanation: Railway tracks expand in length due to heat, requiring gaps for expansion.