Difference between intermediate and activated complex

The activated complex is an unstable (unobserved) structure corresponding to an energy maximum in the reaction profile. An intermediate is the chemical structure present at the transition state. An activated complex can not be isolated or observed in a chemical reaction.

Explanation:

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.

c. 4.54 x 10–12 j happens to be correct