Question 13

(P) Physisorption is an exothermic process ($\Delta H < 0$) and results in a decrease in entropy ($\Delta S < 0$) because the gas molecules are restricted to the surface. Matches (2).

(Q) Graphite is the more stable allotrope of carbon at standard conditions. The conversion of Diamond $\to$ Graphite is exothermic ($\Delta H < 0$) and the entropy increases ($\Delta S > 0$) because graphite has a more disordered layered structure compared to the rigid diamond lattice. Matches (5).

(R) Denaturation of protein involves the unfolding of the highly ordered native structure into a random coil, leading to an increase in entropy ($\Delta S > 0$). This process typically requires energy to break hydrogen bonds, making it endothermic ($\Delta H > 0$). Matches (1).

(S) The conversion of Propene (an open-chain alkene) to Cyclopropane (a strained ring) is endothermic ($\Delta H > 0$) due to the high ring strain in cyclopropane. Entropy decreases ($\Delta S < 0$) during ring formation as the degrees of freedom are reduced. Matches (4).

Correct matching: P-2, Q-5, R-1, S-4. Correct Option: C