Use the potential energy diagram shown to answer the following: Which letter shows the activation energy(without use of a catalyst)

a

Explanation:

Activation energy is the minimum amount of energy that must be overcome before a reaction will proceed to product.

In the energy diagram, the thick line represent the uncatalyzed path while the broken line line indicates the catalyzed path.

In the diagram above, the letter between the reactant and the Peak of the diagram gives the activation energy. This letter is a.

Therefore, the activation energy for the uncatalyzed reaction is 'a'.