20% of N₂O₄ molecules are dissociated in a sample of gas at 27ºC and 760 torr. Mixture has the density at equilibrium equal to

Degree of decomposition, $\alpha =$$\frac{\mathrm{M}-\mathrm{m}}{\mathrm{m}\left(\mathrm{n}-1\right)}$

M = MW of undissociated species

m = MW of equilibrium mixture (observed molecular weight)

n = number of particles produced by the dissociation of one molecule

N₂O_4(g)$\rightleftharpoons$2NO_2(g)

n = 2

α = 0.2

T = (27 + 273)K

P = 760 torr (or) 1 atm

Observed molecular weight = 76.66

for an ideal gas, density (d)