Thermodynamics

Concept:Use thermodynamic sign conventions for $\Delta H$ and $\Delta S$ in each process.Explanation:Physisorption (P): Gas molecules get adsorbed on a solid surface with weak van der Waals forces. The process is exothermic: $\Delta H < 0$. Gas to solid reduces disorder: $\Delta S < 0$. So (P) matches (2).Diamond → Graphite (Q): Graphite is more stable than diamond under normal conditions. The transformation releases energy: $\Delta H < 0$. Graphite layers have higher freedom and disorder: $\Delta S > 0$. So (Q) matches (5).Denaturation of Protein (R): Heat or chemicals break the protein’s native structure. Bond breaking absorbs heat: $\Delta H > 0$. Unfolding increases randomness: $\Delta S > 0$. So (R) matches (1).Propene → Cyclopropane (S): Open-chain propene cyclizes to a strained three‑membered ring. The angular strain stores energy: $\Delta H > 0$. Cyclic structure reduces rotational freedom: $\Delta S < 0$. So (S) matches (4).Answer:P → 2; Q → 5; R → 1; S → 4(Option C).