Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): During the adiabatic free expansion of an ideal gas, the temperature of the gas decreases. Reason (R): In free expansion, the gas expands against zero external pressure doing no work, and since the process is adiabatic, the internal energy remains constant. In the light of the above statements, cho

Step-by-step solution

Assertion (A) is incorrect. For the adiabatic free expansion of an ideal gas, the temperature remains constant ( T = 0 ), it does not decrease. Reason (R) is correct. Free expansion means expansion against vacuum ( P_ ext = 0 ), so work done w = 0 . Since the process is adiabatic, heat exchange q = 0 . According to the first law of thermodynamics, U = q + w = 0 . For an ideal gas, internal energy depends only on temperature, so T = 0 . Answer: Assertion is incorrect but Reason is correct.