Read the Assertion and Reason below and choose the correct option. — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

In adiabatic free expansion, $q = 0$ and $W = 0$ (since expansion is against a vacuum). Thus, $\Delta U = 0$. However, for a non-ideal (real) gas, internal energy depends on both temperature and volume. The change in volume leads to a change in temperature (Joule-Thomson cooling or heating effect). Thus, Statement I is incorrect while Statement II is correct.