The following reaction is exothermic

Which change would shift the equilibrium over to the left

2SO2 (g) + O2 (g) = 2SO3 (g)

Answer: Increase in temperature

Explanation:

Once there is an increase in temperature of the exothermic reaction, the equilibrium position shifts to the left since equilibrium constant, K decreases; hence favoring the formation of reactants which are 2SO2 (g) and O2 (g).

Decrease in temperature, on the other hand, would shift the equilibrium to the right since equilibrium constant, K increases.

Thus, for the exothermic reaction 2SO2 (g) + O2 (g) = 2SO3 (g) : increase in temperature would shift the equilibrium over to the left.