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JEE Main2018ChemistryThermodynamics (C)Actual

For which of the following processes, ∆ S is negative?

Options

  1. AC   diamond → C   ( graphite )
  2. BN 2 g , 1 atm → N 2 ( g ,   5   atm )
  3. CN 2 g ,   273 K → N 2 ( g ,   300 K )
  4. DH 2 g → 2 H ( g )

Correct answer

B. N 2 g , 1 atm → N 2 ( g ,   5   atm )

Step-by-step solution

N 2   g ,   1   atm →   N 2   ( g ,   5   atm ) ∆ S = nC v ln T 2 T 1 + nRln V 2 V 1 For isothermal process T 1 =   T 2 and   V 2 V 1 =   P 1 P 2 = 0 + nRln ⁡ P 1 P 2 = nRln ⁡ 1 5 ∆ S < 0

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