A mixture of NO2  and N2O4 has a vapour density of 38.3 at 300 K. What is the number of moles of NO2 in 100 g of the mixture ?

Molecular weight of mix. = 2 x V.D                                        =2 x 38.3 = 76.6 gWeight of NO2      = xSo that weight of N2O4 = 100 - xHence, x46+100−x92  = 10076.6=2x+100−x92  = 10076.6     x = 20.10 g the number of moles of NO2 =  20.1046=0.437