In thermodynamic process for free expansion, select the 'WRONG' statement out of the following options. (a) Free expansions are adiabatic expansions and there is no exchange of heat between system and environment. (b) A free expansion can be plotted on a p-V diagram. (c) There is no work done on the system or by the system. (d) It is an instantaneous change and the system is not in thermodynamic equilibrium.

Answer: (b). (a) Free expansion is adiabatic, Q = 0: true. (c) Gas expands into vacuum, so W = 0: true. (d) It is sudden and the system is not in equilibrium: true. (b) Non-equilibrium states cannot be plotted on a p - V diagram, so (b) is wrong. So the answer is (b).

In thermodynamic process for free expansion, select the 'WRONG'… | MHT CET 2026 (18 Apr, Shift 1)

Q7MHT CET 2026 · 18 APR · SHIFT 1Easy

P-V Diagrams & Cyclic Processes

In thermodynamic process for free expansion, select the 'WRONG' statement out of the following options.

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Answer: (b)

(a) Free expansion is adiabatic, $Q = 0$ : true.
(c) Gas expands into vacuum, so $W = 0$ : true.
(d) It is sudden and the system is not in equilibrium: true.
(b) Non-equilibrium states cannot be plotted on a $p$ - $V$ diagram, so (b) is wrong.
So the answer is (b).

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