If PCl5 is 80% dissociated at 523 K, what is the vapour density of the equilibrium mixture at 523 K ?

The vapour density of N2O4 at a certain temperature is 30. What is the percentage dissociation of N2O4 at this temperature?

The vapour density of a mixture containing NO 2​ and N 2​ O 4​ is 38.3 at 27 °C. Calculate the moles of NO2​ in 100 mole mixture.