At 227oC one mole of Cl2 and 3 moles of PCl5 are placed in a 100 litre container and allowed to reach equilibrium. It is found that the equilibrium pressure is 2.05 atmospheres. Assuming ideal behaviour, the degree of dissociation 'x' for PCl5 and Kp for the reaction PCl5 (g) ⇌PCl3 (g) + Cl2 (g) is: