Given below are two statements: one labelled as Assertion A and other is labelled as Reason R : Assertion A: A reaction can have zero activation energy Reason R: The minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to threshold value, is called activation energy.

Step-by-step solution

Activation energy is defined as the minimum amount of extra energy required by a reacting molecule to get converted into a product. If   E a = 0 , then according to Arrhenius equation k = Ae − E a / RT = Ae 0 = A . This implies that every collision results into a chemical reaction which cannot be true. So, a reaction cannot have zero activation energy.