‘x’ moles of ${\mathrm{N}}_2{\mathrm{O}}_4$ is taken at ${\mathrm{P}}_1$ atm in a closed vessel & heated. When 75% of ${\mathrm{N}}_2{\mathrm{O}}_4$ dissociated at equilibrium, total pressure at equilibrium was found to be ${\mathrm{P}}_2$ atm. The relation between ${\mathrm{P}}_1 \mathrm{and} {\mathrm{P}}_2$ is

Initial moles of N₂O₄ = x

Initial pressure of N₂O₄ = P₁

Degree of decomposition of N₂O₄

moles of N₂O₄ decomposed = 0.75x

moles of N₂O₄ at equilibrium = (x - 0.75 x) =0.25x

Equiolibrium pressure = P₂

1 mole of N₂O₄ gives 2 moles of NO₂

0.75 moles  of N₂O₄ gives _____ of NO₂

moles of NO₂ formed at equilibrium = 1.5x

Intial moles	x		-	Inital pressure = P1
Moles at equilbrium	(x - 0.75x)		1.5x	Equilibrium pressure = P2

Total moles at equilibrium = x - 0.75x + 1.5x =1.75x

Pressure of gas α number of moles