10th class Physics, Chapter 10: Thermal Physics MCQs

1. When the temperature of a rod of copper is increased, its length:

1. (A) remains the same
2. (B) increases ✓
3. (C) decreases
4. (D) becomes double

2. The amount by which unit length of a material increases when the temperature is raised to 1 °C, is called the coefficient of:

1. (A) cubic expansion
2. (B) volume expansion
3. (C) linear expansion ✓
4. (D) none of these

3. What does a liquid turn into once it is evaporated?

1. (A) Gas
2. (B) Water vapours
3. (C) Air
4. (D) Both (a) and (b) ✓

4. Which property determines how much heat a solid can absorb before its temperature changes significantly?

1. (A) Density
2. (B) Specific heat capacity ✓
3. (C) Colour
4. (D) Hardness

5. High-temperature superconductors typically involve which type of material?

1. (A) Pure metals
2. (B) Organic compounds
3. (C) Ceramics ✓
4. (D) Liquid crystals

6. Thermal expansion is the change in length, area or volume of a substance when it is:

1. (A) heated ✓
2. (B) compressed
3. (C) magnetised
4. (D) electrified

7. When a substance is cooled, its particles:

1. (A) gain energy and move apart
2. (B) stop moving completely
3. (C) become heavier
4. (D) lose energy and move closer together ✓

8. The change in length ΔL of a solid is directly proportional to:

1. (A) its mass only
2. (B) its colour
3. (C) the square of its density
4. (D) its original length and the temperature change ✓

9. The SI unit of the coefficient of linear expansion α is:

1. (A) K⁻¹ ✓
2. (B) K
3. (C) m K⁻¹
4. (D) J K⁻¹

10. The relation giving the final length L of a heated rod is:

1. (A) L = α ΔT / L₀
2. (B) L = L₀ (1 + α ΔT) ✓
3. (C) L = L₀ α ΔT
4. (D) L = L₀ / (1 + α ΔT)

11. Which of the following has the largest coefficient of linear expansion (Table 10.1)?

1. (A) Tungsten
2. (B) Pyrex glass
3. (C) Aluminium ✓
4. (D) Steel

12. The coefficient of linear expansion of steel is about:

1. (A) 8.6 × 10⁻⁵ K⁻¹
2. (B) 0.4 × 10⁻⁵ K⁻¹
3. (C) 1.2 × 10⁻⁵ K⁻¹ ✓
4. (D) 2.4 × 10⁻⁵ K⁻¹

13. Which of the following solids has the smallest coefficient of linear expansion in Table 10.1?

1. (A) Gold
2. (B) Tungsten ✓
3. (C) Brass
4. (D) Copper

14. The coefficient of volume expansion β is given by:

1. (A) ΔV / (V₀ ΔT) ✓
2. (B) ΔT / (V₀ ΔV)
3. (C) V₀ ΔT / ΔV
4. (D) ΔV × V₀ × ΔT

15. A metal rod 2 m long is heated through 50 °C. If α = 2 × 10⁻⁵ K⁻¹, its increase in length is:

1. (A) 20 mm
2. (B) 2 mm ✓
3. (C) 4 mm
4. (D) 0.2 mm

16. The change in volume of a liquid on heating is given by:

1. (A) ΔV = β V₀ ΔT ✓
2. (B) ΔV = V₀ / β ΔT
3. (C) ΔV = β ΔT / V₀
4. (D) ΔV = β V₀ / ΔT

17. Which one of the following relations is correct for the expansion of a liquid in a flask (Fig. 10.3)?

1. (A) Apparent expansion = real expansion + expansion of the flask
2. (B) Real expansion = apparent expansion × expansion of the flask
3. (C) Real expansion = apparent expansion + expansion of the flask ✓
4. (D) Real expansion = apparent expansion − expansion of the flask

18. The real expansion of a liquid is always ____ the apparent expansion.

1. (A) equal to
2. (B) half of
3. (C) greater than ✓
4. (D) less than

19. Why might a completely filled bottle of water crack when put in a freezer?

1. (A) The water becomes lighter in colour
2. (B) The bottle becomes heavier
3. (C) The water evaporates quickly
4. (D) The water expands as it freezes ✓

20. Charles' law states that the volume of a gas is directly proportional to its temperature at constant:

1. (A) pressure ✓
2. (B) mass of the container
3. (C) colour
4. (D) density of the air outside