MHT CET202618 April 2026Morning ShiftPhysicsThermodynamicsActual
In thermodynamic process for free expansion, select the 'WRONG' statement out of the following options.
Options
- AFree expansions are adiabatic expansions and there is no exchange of heat between system and environment.
- BA free expansion can be plotted on a p-V diagram.
- CThere is no work done on the system or by the system.
- DIt is an instantaneous change and the system is not in thermodynamic equilibrium.
Correct answer
B. A free expansion can be plotted on a p-V diagram.
Step-by-step solution
In a free expansion, a gas expands into a vacuum. Since the external pressure is zero, the work done by or on the system is zero ( W = 0 ). The process is typically carried out in an insulated container, meaning there is no heat exchange with the surroundings ( Q = 0 ), making it an adiabatic process. Free expansion is a rapid, highly irreversible process. During the expansion, the gas is not in thermodynamic equilibrium, and macroscopic properties like pressure and temperature are not well-defined. Because interme