Answer:
a. is the energy required for molecules to react with each other
Explanation:
Activation energy may be defined as the extra energy required to start a reaction and the conversion of reactants into its products. It is the energy required to energize or activate molecules or atoms to undergo a transformation or a chemical reaction.
It is necessary for all types of chemical reaction to proceed. With the help of a catalyst the reaction rate increases as the energy of activation lower for the reaction to start.
x or y because both can cause it
