Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R : Assertion A : For a reversible endothermic reaction, the activation energy of the forward reaction is always greater than the enthalpy change ( H ) of the reaction. Reason R : The activation energy of the backward reaction is always a positive quantity. In the light of the above statements, choose the most appropria

Step-by-step solution

The enthalpy change for a reversible reaction is given by the difference between the activation energy of the forward reaction and the backward reaction: H = E_ a(f) - E_ a(b) For an endothermic reaction, H > 0 . Rearranging the equation gives: E_ a(f) = H + E_ a(b) Activation energy is the minimum extra amount of energy required by a reacting molecule to get converted into product, which means it is always a positive quantity. Thus, E_ a(b) > 0 . Substituting a positive value for E_ a(b) in the equation yields: E_