Verified Solution • 2025–26 Session moderate

QJEEM21Cha2ef: JEE Main 2021 Chemistry - Class 11 JEEM21Cha2ef Solution: During which of the following processes, does entropy decrease? …

During which of the following processes, does entropy decrease?

(A) Freezing of water to ice at 0∘C

(B) Freezing of water to ice at −10∘C

(C) N2(g) + 3H2(g) → 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 :

Multiple Choice Options

  • A (A), (C) and (E) only
  • B (B) and (C) only
  • C (A), (B), (C) and (D) only
  • D (A) and (E) only

Step-by-Step Verified Solution

A, B → 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 → No. of molecules decreasing

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

E → NaCl(s) → Na+(aq) + Cl–(aq) ΔS > 0

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

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