Work Done by a Thermodynamic System

Work Done by a Thermodynamic System MDCAT MCQs with answers

16 past paper MCQs on Work Done by a Thermodynamic System, from the Thermodynamics unit of MDCAT Physics. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.The temperature of a given mass of a gas is changed from $150^\circ$C to $300^\circ$C during an isobaric process. The volume of the gas will become: (MDCAT 2022)

  1. half
  2. double
  3. the same
  4. less than double
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Correct answer: (d) less than double

Volume goes as the absolute temperature, and $573/423\approx1.35$, which is less than twice.

2.Bursting of tire is an example of which process? (NUMS MDCAT 2025)

  1. Adiabatic
  2. Isochoric
  3. Isothermal
  4. Isobaric
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Correct answer: (a) Adiabatic

The air escapes too fast for any heat to be exchanged, so the expansion is adiabatic.

3.A gas expands from 1 m^3 to 3 m^3 at constant pressure of 2 Pa. Work done is: (SIBA MDCAT 2025)

  1. 2J
  2. 4J
  3. 6J
  4. 8J
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Correct answer: (b) 4J

$W=P\Delta V=2\times2$, which is $4\,\mathrm{J}$.

4.During the isothermal process, the temperature (UHS MDCAT 2024)

  1. remains constant during the initial phase of the process of the process
  2. remains constant throughout the process
  3. alters throughout the process
  4. increases throughout the process
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Correct answer: (b) remains constant throughout the process

Isothermal means at one temperature, held so throughout the change.

5.In an adiabatic process, how does the temperature of a gas change as its volume decreases? (KMU MDCAT 2024)

  1. The temperature decreases
  2. The temperature increases
  3. The temperature remains constant
  4. The temperature first increases then decreases
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Correct answer: (b) The temperature increases

No heat can escape, so the work done in compressing the gas all goes into its internal energy.

6.During an isothermal expansion of an ideal gas, which of the following statement is true? (KMU MDCAT 2024)

  1. Pressure and temperature of the gas increase
  2. The internal energy of the gas increases
  3. The temperature of the gas remains constant
  4. The work done by the gas is zero
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Correct answer: (c) The temperature of the gas remains constant

Isothermal means at constant temperature, held so by heat flowing in as the gas does work.

7.When a gas is compressed isothermally, the product of its pressure and volume during the process is: (UHS MDCAT 2023)

  1. not constant
  2. constant
  3. zero
  4. proportional to entropy
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Correct answer: (b) constant

At constant temperature $PV=nRT$ makes the product constant, which is Boyle’s law.

8.Temperature of given mass of a gas is changed from 150°C to 300°C during an isobaric process, volume of the gas will become: (UHS MDCAT 2023)

  1. Half
  2. Double
  3. Remain same
  4. Less than double
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Correct answer: (d) Less than double

On the Kelvin scale the temperature rises from $423$ to $573$, a factor of only $1.35$.

9.The thermodynamic process during which volume of the system remains constant is called: (SZABMU MDCAT 2023)

  1. Isothermal
  2. Isobaric
  3. Isochoric
  4. Adiabatic
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Correct answer: (c) Isochoric

A change at constant volume is isochoric.

10.The conditions for application of Boyle’s law holds good in: (SZABMU MDCAT 2023)

  1. Adiabatic process
  2. Isothermal process
  3. Isobaric process
  4. Isochoric process
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Correct answer: (b) Isothermal process

Boyle’s law holds at constant temperature, that is in an isothermal change.

11.In isochoric process: (NUMS MDCAT 2023)

  1. Pressure is kept constant
  2. Exchange of heat is zero
  3. Volume is kept constant
  4. Temperature is kept constant
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Correct answer: (c) Volume is kept constant

Isochoric means at constant volume.

12.The thermodynamic process during which the pressure is kept constant is called: (NUMS MDCAT 2022)

  1. Isochoric process
  2. Adiabatic proms
  3. Isobaric proem
  4. Isothermal proem
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Correct answer: (c) Isobaric proem

A change at constant pressure is isobaric.

13.Which of this is constant in isochoric process? (PMC Practice 2021)

  1. Total heat
  2. Work done
  3. Entropy
  4. Internal energy
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Correct answer: (b) Work done

The volume does not change, so no work is done at any stage.

14.A gas expands from V1 to V2 at pressure P. Work done is: (PMC Practice 2021)

  1. P/(V2-V1)
  2. (P2-P1) * V
  3. P(V1V2/(V2-V1))
  4. P(V2-V1)
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Correct answer: (d) P(V2-V1)

At constant pressure the work done is $P(V_2-V_1)$.

15.Isothermal process can be defined as? (PMC Practice 2021)

  1. PV = constant
  2. PV = RT
  3. PIV = constant
  4. P/V = Nrt
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Correct answer: (a) PV = constant

At constant temperature $PV=nRT$ makes the product constant.

16.The rapid escape of air from a burst tyre is an example of: (UHS MDCAT 2016)

  1. Adiabatic processes
  2. Isothermal process
  3. Cooling process
  4. First law of thermodynamics
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Correct answer: (a) Adiabatic processes

The air escapes far too fast for any heat to be exchanged.

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