MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

During the adsorption of a gas, the gas molecules are restricted to the surface of the solid, which decreases their randomness or entropy. Thus, the change in entropy, S, is negative. For a process to be spontaneous, the change in Gibbs free energy, G, must be negative. According to the Gibbs-Helmholtz equation: G = H - T S Since S is negative, the term -T S becomes positive. For G to be negative, the enthalpy change, H, must be negative and its magnitude must be large enough to overcome the positive -T S term. Therefore, S is negative and H should be highly negative. Answer: S is negative and therefore, H should be highly negative.