138 gm `N_2O_4` is introduced into 8.21 litre container at 300 K. Temperature is increased to 600 K where it dissociates into `NO_2`.If equilibrium partial pressure of `N_2O_4` and `NO_2` are equal than `K_p` (in atm ) for `N_2O_4(g) hArr 2NO_2` at 600 K.