PCl5(g)⇌PCl3(g)+Cl2(g)
Initial5 0 0molesEquilibrium5−x x xmoles
Number of moles of N2=2
Equilibrium pressure =2.46 atm
Total no. of moles = moles of N2 (inert gas) + equilibrium moles,
n=2+(5−x)+x+x
Peq=(7+x)×0.082×600200=2.46
On solving, x=3
∴Kp=(3P10)(3P10)(2P10)=9×2.4620
=1107×10−3 atm