Correct Answer - D
The energy of activation for the reverse reaction will decided by the fact where the reversible is exothermic or endothermic.
For an exothermic reaction `(Delta_(r)H^(Ɵ)is-ve)` thus `(E_(a))_(f)lt(E_(a))_(b)` and for an endothermic reaction `(Delta_(r)H^(Ɵ)is+ve)` Thus `(E_(a))_(f)gt(E_(a))_(b)` . Thus, the energy of activation of reverse reaction is either grater or less than `50Kcal` .