Physics Thermodynamics Free Mock Test: 30 MCQs Free Mock Test

 

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Unit : Thermodynamics Mock Test (30 MCQs)

Test Guidelines:

• Total Questions: 30
• Correct Answer: +1 Mark
• Click "Submit Test" at the bottom to see your score and explanations.

1. If two systems are in thermal equilibrium with a third system, they are in equilibrium with each other. This is?

A) First Law B) Second Law C) Zeroth Law D) Third Law

Correct: C. Zeroth law defines thermal equilibrium and temperature.

2. Internal energy of an ideal gas is a function of:

A) Pressure B) Temperature C) Volume D) Density

Correct: B. For ideal gases, U depends only on T.

3. In an isothermal process, which remains constant?

A) Temperature B) Pressure C) Volume D) Heat

Correct: A. 'Isothermal' means constant temperature.

4. First law of thermodynamics is based on conservation of:

A) Mass B) Momentum C) Energy D) Charge

Correct: C. Heat added = ΔU + Work done.

5. Process in which no heat enters or leaves the system is:

A) Isothermal B) Isobaric C) Adiabatic D) Isochoric

Correct: C. In adiabatic process, ΔQ = 0.

6. Work done in an isochoric process is:

A) Zero B) Maximum C) Infinite D) Unity

Correct: A. Since volume is constant (dV=0), Work = P.dV = 0.

7. The equation PV^γ = constant applies to:

A) Isothermal B) Adiabatic C) Isobaric D) Reversible

Correct: B. This is the adiabatic gas equation.

8. Entropy of the universe tends to:

A) Increase B) Decrease C) Stay constant D) Zero

Correct: A. Second law states entropy always increases in natural processes.

9. Efficiency of a Carnot engine depends on:

A) Nature of gas B) Pressure C) Temperature of Source/Sink D) Volume

Correct: C. η = 1 - T_sink/T_source.

10. Sudden expansion of a gas is:

A) Isothermal B) Adiabatic C) Isobaric D) Isochoric

Correct: B. Sudden changes are adiabatic as heat doesn't get time to exchange.

11. In a cyclic process, change in internal energy is:

A) Zero B) Positive C) Negative D) Infinite

Correct: A. Initial and final states are same.

12. CP - CV = R is known as:

A) Newton's relation B) Mayer's relation C) Boyle's Law D) Charles' Law

Correct: B. Mayer's formula for ideal gases.

13. Which is a state function?

A) Work B) Heat C) Internal Energy D) None

Correct: C. U depends on state, not path.

14. Second law of thermodynamics defines:

A) Temperature B) Energy C) Entropy D) Work

Correct: C. Concept of entropy comes from the Second Law.

15. Area under P-V curve represents:

A) Work Done B) Pressure Change C) Internal Energy D) Entropy

Correct: A. ∫PdV is work.

16. For monoatomic gas, γ is:

A) 1.40 B) 1.67 C) 1.33 D) 1.00

Correct: B. γ = 5/3 = 1.67 for monoatomic gases.

17. Slope of adiabatic curve is how many times isothermal curve?

A) 1 B) γ C) γ-1 D) 1/γ

Correct: B. Adiabatic slope = γ × Isothermal slope.

18. A heat engine converts heat into:

A) Work B) Pressure C) Volume D) Liquid

Correct: A. Engines transform thermal energy into mechanical work.

19. At absolute zero, entropy of perfect crystal is:

A) Maximum B) Zero C) Infinite D) Constant

Correct: B. Third law of thermodynamics.

20. Which law explains direction of heat flow?

A) First Law B) Second Law C) Zeroth Law D) Third Law

Correct: B. Heat naturally flows from hot to cold.

21. For isothermal expansion of ideal gas:

A) dQ = 0 B) dU = 0 C) dW = 0 D) None

Correct: B. Temperature is constant, so U is constant.

22. Refrigerator works on which cycle?

A) Reverse Carnot B) Forward Carnot C) Diesel Cycle D) Otto Cycle

Correct: A. It's a heat engine in reverse.

23. Melting of ice is an _______ process.

A) Isothermal B) Adiabatic C) Isochoric D) None

Correct: A. Phase change occurs at constant temperature.

24. Boyle's Law applies to:

A) Isothermal B) Adiabatic C) Isobaric D) None

Correct: A. PV = k at constant T.

25. Cp/Cv for diatomic gas like Oxygen is:

A) 1.67 B) 1.40 C) 1.33 D) 1.00

Correct: B. γ = 7/5 = 1.4 for diatomic.

26. Work done by system is taken as:

A) Positive B) Negative C) Zero D) Constant

Correct: A. Chemistry and Physics sign conventions can differ, but in standard Physics, work by system expansion is positive.

27. Unit of entropy is:

A) Joule B) J/K C) Watt D) Pascal

Correct: B. dS = dQ/T.

28. Isothermal process occurs:

A) Very Slowly B) Very Fast C) Instantly D) Never

Correct: A. Slow processes allow temperature to equalize.

29. Internal energy of a real gas depends on:

A) T only B) T and V C) P only D) Mass only

Correct: B. Real gases have intermolecular forces, so V matters too.

30. Work done during cyclic process is equal to area of:

A) The PV Loop B) Under the curve C) Y-axis D) Triangle

Correct: A. Net work in a cycle is the area inside the loop.

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