Medium MCQ +4 / -1 PYQ · JEE Mains 2021

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 :

  1. A (A), (C) and (E) only
  2. B (B) and (C) only
  3. C (A), (B), (C) and (D) only Correct answer
  4. D (A) and (E) only

Solution

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.<br><br> C $\to$ No. of molecules decreasing<br><br> D $\to$ Adsorption will lead to decrease in randomness of gaseous particles.<br><br> E $\to$ NaCl(s) $\to$ Na<sup>+</sup>(aq) + Cl<sup>–</sup>(aq) $\Delta$S &gt; 0<br><br> So, (A, B, C, D) decreases entropy.

About this question

Subject: Chemistry · Chapter: Thermodynamics · Topic: Zeroth and First Law

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