1) A moles of PCl5 is heated in a closed container to equilibrium PCl5⇌PCl3(g)+Cl2(g) at a pressure of p atm. If x moles of PCl5 disscociate at equilibrium , then A) xa=KpKp+P B) xa=(Kp+PKp)1/2 C) xa=(KpP)1/2 D) xa=(KpKp+P)1/2 Answer: Option DExplanation: PCl5⇌PCl3(g)+Cl2(g) 1-α α α α = x/a (degree of dissociation ) Total moles = 1−α+α+α=1+α Kp=PPCl3×PCl2PPCl5 =[α1+α.p][α1+α.p]1−α1+α.p =α2p1−α2⇒α=(KpKp+P)1/2