Concept:According to Le Chatelier’s principle, changing pressure shifts equilibrium toward the side with more or fewer gas moles.Explanation:The reaction is: N2O4(g)→2NO2(g).The reactant side has 1 mole of gas, while the product side has 2 moles of gas.A decrease in pressure favors the side with more gas molecules, which is the product side here.Thus, more NO2 will be formed.Options A, B, and D either do not affect the equilibrium or increase pressure, which would favor the reactant side.Answer:C. a decrease pressure