True or false high temperatures reduce activation energy

False.

Explanation:

Activation energy ΔGₐ is only directly affected by the shape of the reaction coordinate curve, and is a function of kinetics.

Activation energy ΔGₐ is the minimum amount of energy needed to overcome the process of the reactant into the transition state, and finally the product. Reaction coordinate diagrams are purely based on potential energy of the molecules (electronic structure).

The rate at which the reaction will occur may change due to high temps, but not the actual ΔGₐ. To better understand, look at the Arrhenius equation. Ea (activation energy) is a constant, and is not affected by temperature changes. The rate constant k is only affected by temperature change.