Class 11 Physics (NCERT)

1. The SI unit of temperature is

• A. Kelvin
• B. Celsius
• C. Fahrenheit
• D. Joule

2. The relationship between Celsius and Kelvin scale is

• A. T(K) = t(°C) + 273.15
• B. T(K) = t(°C) - 273.15
• C. T(K) = t(°C) × 273.15
• D. T(K) = t(°C)/273.15

3. The increase in length per unit original length per degree rise in temperature is called

• A. Coefficient of linear expansion
• B. Coefficient of volume expansion
• C. Coefficient of superficial expansion
• D. Thermal conductivity

4. For an ideal gas, the relation between coefficients of linear (α), superficial (β), and cubical (γ) expansion is approximately

• A. α : β : γ = 1 : 2 : 3
• B. α : β : γ = 1 : 3 : 2
• C. α : β : γ = 3 : 2 : 1
• D. α : β : γ = 2 : 1 : 3

5. Water shows anomalous expansion between

• A. 0°C and 4°C
• B. 4°C and 100°C
• C. -4°C and 0°C
• D. 4°C and 10°C

6. The amount of heat required to raise the temperature of a unit mass of a substance by one degree is called

• A. Specific heat capacity
• B. Latent heat
• C. Thermal capacity
• D. Molar heat capacity

7. The heat required to change the state of a unit mass of a substance without changing its temperature is called

• A. Latent heat
• B. Specific heat
• C. Sensible heat
• D. Radiant heat

8. The specific heat capacity of water is

• A. 4186 J/kg·K
• B. 2100 J/kg·K
• C. 1000 J/kg·K
• D. 500 J/kg·K

9. Heat transfer through a solid medium without actual movement of particles is called

• A. Conduction
• B. Convection
• C. Radiation
• D. Diffusion

10. Heat transfer through fluids by actual movement of particles is called

• A. Convection
• B. Conduction
• C. Radiation
• D. Insulation

11. Heat transfer that does not require a medium is called

• A. Radiation
• B. Conduction
• C. Convection
• D. Conduction and convection both

12. According to Stefan-Boltzmann law, the energy radiated per unit time by a black body is proportional to

• A. The fourth power of its absolute temperature
• B. The square of its absolute temperature
• C. Its absolute temperature directly
• D. The square root of its absolute temperature

13. Wien's displacement law relates the wavelength of maximum emission of a black body to its

• A. Absolute temperature (inversely)
• B. Absolute temperature (directly)
• C. Surface area
• D. Emissivity only

14. A perfect black body is one that

• A. Absorbs all radiation incident on it
• B. Reflects all radiation incident on it
• C. Transmits all radiation incident on it
• D. Neither absorbs nor emits radiation

15. Newton's law of cooling states that the rate of loss of heat of a body is proportional to

• A. The temperature difference between the body and its surroundings
• B. The square of the temperature difference
• C. The absolute temperature of the body only
• D. The mass of the body

16. Which mode of heat transfer allows the Sun's energy to reach the Earth?

• A. Radiation
• B. Conduction
• C. Convection
• D. Diffusion

17. Land and sea breezes are examples of heat transfer by

• A. Convection
• B. Conduction
• C. Radiation
• D. Evaporation only

18. The triple point of water on the Kelvin scale is

• A. 273.16 K
• B. 273.15 K
• C. 373.16 K
• D. 0 K

19. A bimetallic strip bends on heating because the two metals have

• A. Different coefficients of linear expansion
• B. The same coefficient of linear expansion
• C. Different specific heat capacities only
• D. Different melting points only

20. Which of these correctly ranks thermal conductivity from highest to lowest?

• A. Metals > liquids > gases
• B. Gases > liquids > metals
• C. Liquids > metals > gases
• D. Gases > metals > liquids

21. The process of change from liquid to vapour state at any temperature below the boiling point is called

• A. Evaporation
• B. Boiling
• C. Condensation
• D. Sublimation

22. Evaporation causes cooling because

• A. The escaping molecules carry away kinetic energy, lowering the average energy of the remaining liquid
• B. It increases the pressure of the surroundings
• C. It decreases the surface tension of the liquid
• D. It increases the density of the liquid

23. Direct conversion of a solid into vapour without passing through the liquid state is called

• A. Sublimation
• B. Fusion
• C. Vaporization
• D. Condensation

24. During melting of ice at 0°C, the temperature of the ice-water mixture

• A. Remains constant until all ice melts
• B. Rises continuously
• C. Falls continuously
• D. Rises then falls

25. Calorimetry is the technique used to measure

• A. Heat exchanged between bodies
• B. Pressure of a gas
• C. Coefficient of expansion
• D. Density of a liquid

26. Why is a car radiator often painted black?

• A. Black surfaces are better emitters and absorbers of radiant heat
• B. Black paint is cheaper
• C. It reduces conduction of heat
• D. It has no relation to heat transfer

27. Woollen clothes keep us warm in winter mainly because

• A. Air trapped in wool is a poor conductor of heat
• B. Wool generates heat by itself
• C. Wool has very high thermal conductivity
• D. Wool absorbs cold from the body

28. Two bodies at different temperatures placed in contact will eventually reach

• A. Thermal equilibrium at a common temperature
• B. The same specific heat
• C. The same mass
• D. Zero temperature

29. Why do railway tracks have small gaps left between rail segments?

• A. To allow for thermal expansion of the rails in summer
• B. To reduce the weight of the tracks
• C. To allow water drainage
• D. To make the tracks cheaper to manufacture

30. On a cold morning, a metal door handle feels colder to touch than a wooden door, though both are at the same temperature, because

• A. Metal has higher thermal conductivity and conducts heat away from the hand faster
• B. Metal is actually at a lower temperature than wood
• C. Wood absorbs heat from the surroundings
• D. Metal has a higher specific heat capacity than wood