Thermodynamics Online Mcqs Test

Mustansar KhanLast Updated: October 13, 2025

Important Physics Thermodynamics Question and Answer

Total Questions:	49
Time Allowed:	25 Minutes
Total Marks:	49
How to Attempt Test:	Please choose the right Option in MCQ-type question.
Test Helpful For:	Physics Test ECAT Test MDCAT Test FPSC/PPSC/SPSC/KPPSC/BPSC/AJKPSC/NTS Physics Interview Question Answer

Physics Thermodynamics Practice Test Online With Explanation

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1. Molar specific heat is the amount of heat required to:

Melt one mole of substance

Boil one mole of water

Freeze one mole of liquid

Raise the temperature of 1 mole by 1°C

2. If Q = 200 J and W = 50 J, what is the change in internal energy?

250 J

300 J

150 J

100 J

3. What does the term “internal energy” refer to?

Total kinetic and potential energy of molecules

Heat energy only

Energy due to external force

Energy required for phase change

4. The SI unit of heat is:

Calorie

Joule

Watt

Kelvin

5. Which equation represents the first law of thermodynamics?

PV = nRT

Q = mcΔT

F = ma

ΔU = Q – W

6. The first law of thermodynamics violates:

Conservation of energy

Conservation of momentum

Creation of energy

Destruction of mass

7. If no heat is exchanged with the surroundings, the process is called:

Isothermal

Adiabatic

Isobaric

Isochoric

8. Which of the following is a state function?

Internal energy

Work

Heat

Path

9. Which process occurs without any change in heat content?

Isochoric

Isothermal

Adiabatic

Isobaric

10. Which instrument is used to measure heat?

Calorimeter

Voltmeter

Thermometer

Barometer

11. The heat required to raise the temperature of one mole of a substance by one Kelvin is:

Latent heat

Thermal conductivity

Specific heat

Molar heat capacity

12. When a gas expands doing work and absorbs heat, its internal energy:

Decreases

Becomes zero

Remains the same

Increases

13. Which of the following has units J/mol·K?

Internal energy

Molar specific heat

Pressure

Specific heat

14. Which physical quantity is represented by the slope of a temperature vs. heat graph during heating?

Latent heat

Specific heat

Pressure

Internal energy

15. Which gas law is used in the derivation of the first law of thermodynamics?

Dalton’s law

Charles’s law

Ideal gas law

Boyle’s law

16. What is the value of specific heat of water?

4200 J/kg·K

4.2 J/kg·K

420 J/kg·K

0.42 J/kg·K

17. What does an isothermal process imply?

Constant volume

Constant temperature

Constant pressure

Constant entropy

18. What is the heat required to raise the temperature of 5 kg of a substance with specific heat 200 J/kg·K by 3 K?

1000 J

600 J

3000 J

9000 J

19. Which of the following is not a path function?

Heat

All of the above

Internal energy

Work

20. The total energy of an isolated system:

Remains constant

Becomes zero

Increases

Decreases

21. In the equation ΔU = Q – W, what does a positive W indicate?

No work

Heat absorbed

Work done on the system

Work done by the system

22. Which of the following does not change during an isothermal process?

Volume

Pressure

Heat

Temperature

23. In a system where no heat is added and work is done on the gas, internal energy:

Increases

Decreases

Becomes zero

Remains same

24. Which law defines the mechanical equivalent of heat?

Boyle’s law

Law of conservation of momentum

Newton's law

First law of thermodynamics

25. During isobaric expansion of gas:

No work is done

Volume remains constant

Pressure increases

Pressure remains constant

Page 2 of 2

26. Which of the following is an extensive property?

Specific heat

Pressure

Internal energy

Temperature

27. Which of the following processes occurs at constant volume?

Isothermal

Adiabatic

Isochoric

Isobaric

28. What does a negative ΔU indicate?

Energy is absorbed

System has gained energy

Internal energy has decreased

Temperature increases

29. When W = Q in the first law equation, what is ΔU?

Maximum

Zero

Equal to heat

Minimum

30. Which thermodynamic process has both Q and W equal to zero?

Isothermal

Isochoric

Free expansion

Adiabatic

31. Which of the following has the highest molar specific heat at constant pressure?

Diatomic gases

Metals

Water

Monoatomic gases

32. Which of the following statements is true about heat?

It is stored in the body

It is a form of matter

It flows from hot to cold

It flows from cold to hot

33. What is the unit of specific heat in SI?

J/kg

J/mol·K

J/kg·K

J/K

34. In an adiabatic process, if work is positive:

Temperature remains constant

Internal energy decreases

Internal energy increases

Internal energy remains unchanged

35. What is the heat added in an adiabatic process?

Constant

Infinite

Zero

Equal to work done

36. In which process is ΔU = Q?

Isochoric

Adiabatic

Isothermal

Isobaric

37. In the first law of thermodynamics, the internal energy change is equal to:

Work done by the system

Pressure × Volume

Heat added to the system

Heat added minus work done

38. The temperature of a gas is directly proportional to:

Mass

Internal energy

Pressure only

Volume

39. What is the heat capacity of a substance?

Volume × density

Heat required to raise temperature by 1°C

Heat required to change state

Mass × temperature

40. What is specific heat?

Heat required to change state

Heat required for melting

Heat required to increase pressure

Heat required to raise temperature of 1 kg by 1 K

41. Which process shows ΔU = 0?

Isobaric

Adiabatic

Isochoric

Isothermal

42. Which of the following has the highest specific heat?

Copper

Water

Iron

Mercury

43. Specific heat is lowest for:

Iron

Water

Lead

Aluminum

44. What happens to internal energy during an isothermal expansion?

Becomes negative

Increases

Decreases

Remains constant

45. When a gas is compressed, work is:

Infinite

Zero

Done by the gas

Done on the gas

46. When a system performs positive work, it means:

Energy is released by the system

Pressure increases

Energy is added to the system

Volume decreases

47. Which of the following expresses work done at constant pressure?

W = PV

W = PΔV

W = ΔU

W = Q

48. Which law states that energy can neither be created nor destroyed?

Zeroth law of thermodynamics

Third law of thermodynamics

First law of thermodynamics

Second law of thermodynamics

49. What happens to the internal energy in an adiabatic expansion?

Doubles

Decreases

Becomes zero

Increases

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Mustansar KhanLast Updated: October 13, 2025

Important Physics Thermodynamics Question and Answer

Physics Thermodynamics Practice Test Online With Explanation

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