Question

A gaseous compound of molecular mass 82.1 dissociates on heating to 400K as : $X_2{Y}_{4\left(g\right)}\to X_{2\left(g\right)}+2Y_{2\left(g\right)}$. The density of the equilibrium mixture at a pressure of 1 atm and temperature of 400K is $2.0g{L}^{-1}$. The compound dissociates to the extent of :

• A. 95.1%
• B. 47.6%
• C. 12.5%
• D. None of these

Answer 1

The correct option is C

12.5%

$X_2{Y}_{4\left(g\right)}\rightleftharpoons X_{2\left(g\right)}+2Y_{\left(g\right)}\alpha =\frac{D-d}{d(y-1)},y=3D=\frac{PM}{RT}=\frac{1\times 82.1}{0.0821\times 400}=2.5g{L}^{-1}d=2.0g{L}^{-1}\left(given\right)$