Some reactions are inhibited by the presence of another chemical.

Some reactions are inhibited by the presence of another chemical. Oxidation reactions for instance are often inhibited by the presence of citric acid, hence why it is an ingredient in many packaged foods. It increases the shelf live significantly.

If one trial is carried out for an oxidation reaction in which citric acid was present and one without it present.

a)          What effect (if any) that citric acid has on the activation energy of the oxidation reaction?

b)         What additional information (if any) would require to make the determination in the above question?

c)       Would the activation energy of the oxidation reaction to be higher, lower, or the same with the citric acid present? Please explain.