The reaction between iodine and carbon dioxide to yield diiodine pentoxide is exothermic. How could the yield of diiodine pentoxide be decreased?

Increasing the temperature

Explanation:

According to Le Chatelier's principle, "if any of the conditions of a system in equilibrium is changed, the system will adjust itself in order to annul the effect of the change".

Since the forward reaction is exothermic, this suggests that heat is given off in the reaction.

Increasing the temperature will favors the reverse process which is endothermic.

In going from the reactants to the the products, the reaction is deemed exothermic which suggests that it produces heat.

The backward reaction is endothermic i. e it absorbs heat. If the temperature is increased, this process will be favored and more reactants produced. Less of the diiodine pentoxide will form. There is a leftward shift of the equilibrium