For the process, Ag⇌Bg+Cg the value of Kp in terms of degree of decomposition α of ‘A’ and equilibrium pressure (P) is

Ag⇌ Bg+Cg Initial moles             1          -       - Moles at equilibrium   1-α    α      α Total moles at equilibrium = 1-α+α+α=1+α XA=1-α1+α;   XB=XC=α1+α; Kp=pB,pCpA=α1+αP21-α1+αP=α2P1-α;