Question

Which is the best definition of activation energy? the energy required to end a chemical reaction the energy required to bind a substrate to an active site the energy required to form or break the bonds of reactant molecules the energy required to re-form bonds in product molecules

Answer 1

The energy required to form or break the bonds of reactant molecules.

Answer 2

Activation energy is the minimum quantity of energy that the reacting species must possess in order to undergo a specified reaction.

So the answer : it is the required to form or break the bonds of reactant molecules that results in a chemical reaction.