Question

Adiabatic free expansion of an ideal gas must be: \} \begin{tabular}{ll} (A) Isobaric & (B) Isochoric
(C) Isothermal & (D) Isoentropic
\end{tabular}

• A. Isobaric
• B. Isochoric
• C. Isothermal
• D. Isoentropic

Hint:

Key points summarizing the principles Key Points: In free expansion, no work is done on or by the system ($W=0$). An adiabatic process means no heat is exchanged with the surroundings ($q=0$). For an ideal gas, the internal energy depends only on temperature ($\Delta U \propto \Delta T$), so no change in internal energy implies no temperature change. Entropy increases in a free expansion process, making it irreversible and not isoentropic. A special case of this phenomenon is the Joule expansion, which demonstrates the temperature constancy in an adiabatic free expansion.