An ideal gas goes from state A to state B via three different processes as indicated in the P-V diagram. If Q1, Q2, Q3 indicate the heat absorbed by the gas along the three processes and Δ U1, Δ U2, Δ U3 indicate the change in internal energy along the three processes respectively, then (a) Q1 > Q2 > Q3 and Δ U1 = Δ U2 = Δ U3 (b) Q3 > Q2 > Q1 and Δ U1 = Δ U2 = Δ U3 (c) Q1 = Q2 = Q3 and Δ U1 > Δ U2 > Δ U3 (d) Q3 = Q2 = Q1 and Δ U1 > Δ U2 > Δ U3

Answer: (a). Same initial and final states, so Δ U₁ = Δ U₂ = Δ U₃. Work = area under the curve: path 1 is highest, 3 is lowest, so W₁ > W₂ > W₃. Q = Δ U + W ⇒ Q₁ > Q₂ > Q₃ So the answer is (a).

An ideal gas goes from state A to state B via three different… | NEET 2012 (AIPMT, Mains)

Q81NEET 2012 · AIPMT · MAINSMedium

P-V Diagrams & Cyclic Processes

An ideal gas goes from state A to state B via three different processes as indicated in the P-V diagram.

If Q1, Q2, Q3 indicate the heat absorbed by the gas along the three processes and $\Delta$ U1, $\Delta$ U2, $\Delta$ U3 indicate the change in internal energy along the three processes respectively, then

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Answer: (a)

Same initial and final states, so $\Delta U_1 = \Delta U_2 = \Delta U_3$ .
Work = area under the curve: path 1 is highest, 3 is lowest, so $W_1 > W_2 > W_3$ .
$Q = \Delta U + W \Rightarrow Q_1 > Q_2 > Q_3$
So the answer is (a).

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