Question

The vapour density of a mixture containing $N{O}_2$ and $N_2{O}_4$ is $38.3$ at ${27}^{o}C$. The moles of $N{O}_2$ on $100$ mole mixture is?

• A. $33.48$
• B. $53.52$
• C. $38.3$
• D. $76.6$

Answer 1

The correct option is A $33.48$

Mole mass of minture=$\frac{100}{766}$

Let a g of ${NO}_2$ is present in mixture

moles of ${NO}_2+$ moles of $N_2{O}_4=$ Moles of mixture

$\frac{a}{46}+\frac{100-a}{92}=\frac{100}{78}{\Rightarrow }_{1.3057}\Rightarrow a=20\cdot 19$

mole of ${NO}_2$ in mixture $=\frac{20.10}{46}=0.437.$

$\begin{array}{c}\text{100 mole of}\begin{array}{cc}min& =0.437\times 100\\ & =43.7\\ x& =\frac{43.7}{1.3057}=33.48\end{array}\end{array}$

Hence correct Answer - A