Q13 / 48 · JEE Advanced 2026 (Paper 1) · Chemistry

List-I contains various physical/chemical processes, and List-II contains combinations of changes in enthalpy ($\Delta H$) and entropy ($\Delta S$). Match each entry in List-I to the appropriate entry in List-II, and choose the correct option.
List-IList-II
(P) Physisorption(1) $\Delta H > 0$ and $\Delta S > 0$
(Q) Diamond $\longrightarrow$ Graphite(2) $\Delta H < 0$ and $\Delta S < 0$
(R) Denaturation of protein(3) $\Delta H < 0$ and $\Delta S = 0$
(S) Propene $\longrightarrow$ Cyclopropane(4) $\Delta H > 0$ and $\Delta S < 0$
(5) $\Delta H < 0$ and $\Delta S > 0$

  • A
    P $\rightarrow$ 2; Q $\rightarrow$ 3; R $\rightarrow$ 5; S $\rightarrow$ 4
  • B
    P $\rightarrow$ 4; Q $\rightarrow$ 3; R $\rightarrow$ 5; S $\rightarrow$ 1
  • Correct answer
    C
    P $\rightarrow$ 2; Q $\rightarrow$ 5; R $\rightarrow$ 1; S $\rightarrow$ 4
  • D
    P $\rightarrow$ 2; Q $\rightarrow$ 5; R $\rightarrow$ 1; S $\rightarrow$ 3

Solution

(P) Physisorption is an exothermic process because attractive forces are formed between the adsorbate and the adsorbent, so $\Delta H < 0$. The gas molecules are restricted on the solid surface, decreasing randomness, so $\Delta S < 0$. This matches (2).

(Q) Diamond $\longrightarrow$ Graphite is an exothermic process because graphite is the thermodynamically more stable allotrope of carbon at standard conditions ($\Delta H < 0$). Graphite has a layered structure and is less dense, so it has higher entropy than the rigid 3D network of diamond ($\Delta S > 0$). This matches (5).

(R) Denaturation of protein involves the breaking of hydrogen bonds and the unfolding of its specific 3D structure into a more random coil. Breaking these interactions requires energy ($\Delta H > 0$) and the unfolding increases randomness ($\Delta S > 0$). This matches (1).

(S) Propene $\longrightarrow$ Cyclopropane is an endothermic process because cyclopropane has significant ring strain compared to the open-chain propene, making it less stable ($\Delta H > 0$). The formation of a rigid ring restricts the degrees of freedom (such as rotation around single bonds), decreasing entropy ($\Delta S < 0$). This matches (4).

Thus, P $\rightarrow$ 2, Q $\rightarrow$ 5, R $\rightarrow$ 1, S $\rightarrow$ 4.

Answer: P $\rightarrow$ 2; Q $\rightarrow$ 5; R $\rightarrow$ 1; S $\rightarrow$ 4

Hence, the correct answer is option: 'C'.

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