In the decomposition of PCl5 represented by, PCl5 ⇋ PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5.

Answer: Option A

Since the moles of reactants is less than the products by Le Chatelier's principle we can say decreasing the pressure will increases the dissociation of $$PC{l}_5.$$