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If one mole of an ideal gas at (P_1,V_1) is allowed to expand reversibly and isothermally (A to B) its pressure is reduced to one-half of the…

JEE Main 2021 — Physics Thermodynamics

2021mcqhard

If one mole of an ideal gas at (P1,V1)({P}_{1},{V}_{1})(P1​,V1​) is allowed to expand reversibly and isothermally (AAA to BBB) its pressure is reduced to one-half of the original pressure (see figure). This is followed by a constant volume cooling till its pressure is reduced to one-fourth of the initial value (B→C).(B\rightarrow C).(B→C). Then it is restored to its initial state by a reversible adiabatic compression (CCC to AAA). The net workdone by the gas is equal to:

JEE Main 2021 Physics, Thermodynamics — question figure

Official previous-year question

Held on 24 Feb 2021 · Verified 6 Jul 2026.

Options

  1. A

    000

  2. B

    RTln(2)RT\mathrm{ln}(2)RTln(2)

  3. C

    −RT2(γ−1)-\frac{RT}{2(\gamma -1)}−2(γ−1)RT​

  4. D

    RT[ln(2)−12(γ−1)]RT[\mathrm{ln}(2)-\frac{1}{2(\gamma -1)}]RT[ln(2)−2(γ−1)1​]

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