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JEE Main 2025 (3 Apr, Shift 2) · Thermodynamic Processes

Thermodynamic Processes question from JEE Main 2025 (3 Apr, Shift 2)

Q66JEE Main 2025 · 3 APR · SHIFT 2Medium

Thermodynamic Processes

An ideal gas exists in a state with pressure P0P_0, volume V0V_0. It is isothermally expanded to 4 times of its initial volume (V0)(V_0), then isobarically compressed to its original volume. Finally the system is heated isochorically to bring it to its initial state. The amount of heat exchanged in this process is

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Answer: (b)

VP(P0, V0)P0/4V04V0isothermalisobaric
  1. Cyclic process: ΔU=0\Delta U = 0, so net heat == net work.
  2. Isothermal V0→4V0V_0 \to 4V_0: W1=P0V0ln⁡4=2P0V0ln⁡2W_1 = P_0V_0\ln 4 = 2P_0V_0\ln 2.
  3. Pressure after expansion is P0/4P_0/4; isobaric 4V0→V04V_0 \to V_0: W2=P04(V0−4V0)=−0.75 P0V0W_2 = \dfrac{P_0}{4}(V_0 - 4V_0) = -0.75\,P_0V_0.
  4. Isochoric: W3=0W_3 = 0.
  5. Q=P0V0(2ln⁡2−0.75)Q = P_0V_0(2\ln 2 - 0.75), so the answer is (b).
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