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MHT CET202526 Apr 2025Morning ShiftChemistryThermodynamics (C)Actual

Identify from following the correct set of thermodynamic conditions for the reaction to be nonspontaneous at all temperature.

Options

  1. AH < 0 and S < 0
  2. BH >0 and S >0
  3. CH 0
  4. DH >0 and S < 0

Correct answer

D. H >0 and S < 0

Step-by-step solution

Spontaneity is determined by the Gibbs free energy change: G = H - T S For a reaction to be nonspontaneous at all temperatures, G > 0 must hold regardless of T . A reaction with H > 0 and S Since both terms are positive, G > 0 for all T , ensuring nonspontaneity. Other combinations depend on temperature: H 0 and S > 0 can be spontaneous at high T , and H 0 is always spontaneous. Final answer: D

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