JEE MAIN - Chemistry (2021 - 17th March Evening Shift - No. 7)

During which of the following processes, does entropy decrease?

(A) Freezing of water to ice at 0$$^\circ$$C

(B) Freezing of water to ice at $$-$$10$$^\circ$$C

(C) N2(g) + 3H2(g) $$ \to $$ 2NH3(g)

(D) Adsorption of CO(g) on lead surface.

(E) Dissolution of NaCl in water

Choose the correct answer from the options given below :
(A), (C) and (E) only
(B) and (C) only
(A), (B), (C) and (D) only
(A) and (E) only

Explanation

A, B $$ \to $$ Freezing of water will decrease entropy as particles will move closer and forces of attraction will increase. This leads to decrease in randomness. So entropy decrease.

C $$ \to $$ No. of molecules decreasing

D $$ \to $$ Adsorption will lead to decrease in randomness of gaseous particles.

E $$ \to $$ NaCl(s) $$ \to $$ Na+(aq) + Cl–(aq) $$\Delta $$S > 0

So, (A, B, C, D) decreases entropy.

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