(i) When more PCl5 is added to the reaction mixture, the concentration of PCl5 and Cl2 will increase in such a way that the value of Kc remains unchanged.
(ii) When pressure is increased, the reaction will move in a direction of lower volume, i.e., backwards. As a result, the value of Kc will decrease.
(iii) The reaction is endothermic in nature. Therefore, increase in temperature will favour the forward reaction. As a result, the value of Kc will increase.