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MHT CET202615 April 2026Evening ShiftChemistryThermodynamics (C)Actual

For a reaction to be spontaneous at all temperatures, the values of enthalpy change and entropy change should be

Options

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

Correct answer

B. H 0

Step-by-step solution

For a reaction to be spontaneous, the change in Gibbs free energy must be negative, i.e., G The relationship between G , enthalpy change H , and entropy change S is given by the Gibbs equation: G = H - T S Since absolute temperature T is always positive, for G to be negative at all temperatures, both terms contributing to G must favor spontaneity. This happens when: H S > 0 (increase in entropy) Under these conditions, the term -T S is negative, and since H is also negative, their sum G will always be negative rega

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