When N2O5 is heated at certain temperature, it dissociates as
N2O5(g)⇌N2O3(g)+O2(g);Kc=2.5. At the same time N2O3 also decomposes as:
N2O3(g)⇌N2O+O2(g). If initially 4.0 moles of N2O5 are taken in 1.0 litre flask and allowed to dissociation, concentration of O2 at equilibrium is 2.5M.