FSc Part 1 Physics chapter 11: Heat and thermodynamics MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

28 exam-style questions on Heat and thermodynamics, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

28 questions · 3 topics · 10 per test

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What chapter 11 covers

Ten Heat and thermodynamics questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. In a diesel engine,

  1. A
    the fuel is ignited by a spark plug
  2. B
    the fuel is ignited by air heated through rapid compression
  3. C
    there is no compression stroke
  4. D
    a petrol-air mixture is drawn in on the intake stroke
Show answer

Answer: B. Air alone is compressed so strongly (and nearly adiabatically) that it becomes hot enough to ignite the diesel sprayed into it. Spark plugs are used in petrol engines.

2. The average translational kinetic energy of a gas molecule at 300 K is (k = 1.38 × 10−23 J K−1)

  1. A
    4.14 × 10−21 J
  2. B
    6.21 × 10−21 J
  3. C
    2.07 × 10−21 J
  4. D
    6.21 × 10−23 J
Show answer

Answer: B. ⟨½mv2⟩ = (3/2)kT = 1.5 × 1.38 × 10−23 × 300 = 6.21 × 10−21 J. kT alone gives 4.14 × 10−21 J.

3. A refrigerator transfers heat from its cold interior to the warmer room. This is possible because

  1. A
    the compressor does work on the refrigerant
  2. B
    heat naturally flows from cold to hot
  3. C
    the refrigerant creates cold
  4. D
    the insulated walls produce heat
Show answer

Answer: A. By the second law, heat moves from cold to hot only when external work is done; the compressor supplies this work.

4. Which of these is closest to an adiabatic process?

  1. A
    slow melting of ice on a table
  2. B
    rapid compression of air in a bicycle pump
  3. C
    water boiling in an open pan
  4. D
    slow expansion of a gas in a cylinder kept in a large water bath
Show answer

Answer: B. The compression is so quick that there is no time for heat to leave, so Q ≈ 0 and the air warms up. A slow change in a water bath is isothermal.

5. When a gas expands adiabatically,

  1. A
    its temperature rises
  2. B
    heat flows into it from the surroundings
  3. C
    its temperature falls, because it does work at the expense of its internal energy
  4. D
    its temperature stays constant
Show answer

Answer: C. In an adiabatic change Q = 0, so W = −ΔU. Work done by the expanding gas reduces its internal energy, so it cools.

6. Which of these is NOT a postulate of the kinetic theory of gases?

  1. A
    the molecules are in constant random motion
  2. B
    collisions between molecules are perfectly elastic
  3. C
    there are strong attractive forces between molecules at all distances
  4. D
    the volume of the molecules is negligible compared with the volume of the container
Show answer

Answer: C. Kinetic theory assumes no forces between molecules except during collisions. Strong attractions would make the gas non-ideal.

7. A gas occupies 2.0 L at 27 °C. It is heated at constant pressure to 327 °C. Its new volume is

  1. A
    24.2 L
  2. B
    4.0 L
  3. C
    2.2 L
  4. D
    3.0 L
Show answer

Answer: B. Charles's law uses kelvin: V2 = 2.0 × 600/300 = 4.0 L. Using °C (327/27) gives the wrong 24.2 L.

8. 500 J of heat is supplied to a gas, and the gas does 200 J of work on its surroundings. The change in its internal energy is

  1. A
    +300 J
  2. B
    +700 J
  3. C
    −300 J
  4. D
    +500 J
Show answer

Answer: A. Q = ΔU + W, so ΔU = 500 − 200 = +300 J. Adding them (700 J) counts the work the wrong way.

9. 1.0 kg of ice melts at 0 °C. The latent heat of fusion is 3.36 × 105 J kg−1. The change in entropy of the ice is

  1. A
    3.36 × 105 J K−1
  2. B
    9.2 × 107 J K−1
  3. C
    1.23 J K−1
  4. D
    1.23 × 103 J K−1
Show answer

Answer: D. ΔS = ΔQ/T = 3.36 × 105/273 = 1.23 × 103 J K−1. The temperature must be in kelvin; multiplying by T gives 9.2 × 107.

10. For an ideal gas Cv = 20.8 J mol−1 K−1. Taking R = 8.31 J mol−1 K−1, Cp is

  1. A
    12.5 J mol−1 K−1
  2. B
    20.8 J mol−1 K−1
  3. C
    29.1 J mol−1 K−1
  4. D
    8.31 J mol−1 K−1
Show answer

Answer: C. Cp − Cv = R, so Cp = 20.8 + 8.31 = 29.1 J mol−1 K−1. Subtracting gives 12.5, which is wrong since Cp > Cv.

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Ways to practise this chapter

Heat and thermodynamics: questions students ask

How many Heat and thermodynamics MCQs are there?

28, each with the answer and a short explanation, across 3 topics: Kinetic theory of gases, Internal energy and the first law of thermodynamics, Second law, heat engines and entropy. Every chapter test draws ten of them, so you can take it many times.

Is the FSc Part 1 Physics chapter 11 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

Can I read the explanations in Urdu?

Yes. In practice mode and on your results you can switch the explanations to Urdu.

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