Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction ?

A spontaneous reaction occurs when the Gibbs free energy change (∆G) is negative. The equation for ∆G is ∆G = ∆H - T∆S, where ∆H is the enthalpy change and ∆S is the entropy change. For a reaction to be spontaneous, ∆G must be negative. This can happen in two scenarios: (1) when ∆H is negative (exothermic reaction) and ∆S is positive (increasing disorder), or (2) when T∆S > ∆H, meaning the entropy term dominates, even if ∆H is positive (endothermic reaction), as long as ∆S is positive and the temperature is high enough. Therefore, the correct pair that is certain to result in a spontaneous reaction is an exothermic reaction with increasing disorder.