3 moles of PCI₅(g) is present in a closed vessel ofcapacity one litre. At equilibrium, only half of the moles of PCI₅ initially taken are observed to be present in container. The equilibrium constant of reaction,
PCI₅(g) ⇌ PCI₃ (g)+Cl₂ (g), is
a) 1.5
b) 4.5
c) 6.0
d) 9.0