A vessel of volume `V = 5` litre contains `1.4 g` nitrogen and `0.4g` of He at `1500K`. If `30%` of the nitrogen molecules are disassociated into atoms then the gas pressure becomes `(N)/(8)xx10^(5)N//m^(2)`. Find `N` (Assume `T` constant). `[R = (25)/(3)J//molK]`