N2O4(g)⇌2NO2(g)
At equi. (1−x) 2x
x (degree of dissociation) =D−d(n−1)d
Given, d=38.3;D=Mol.massofN2O42=922=46;n=2
So, x=46−38.338.3=0.2
At equilibrium, amount of N2O4=1−0.2=0.8mol
and amount of NO2=2×0.2=0.4mol
Mass of the mixture=0.8×92+0.4×46
=92.0g
Since, 92 gram of themixture contains =0.4mol NO2
100 gram of the mixture contains ==0.4×10092=0.43 mol NO2