Question

A gaseous mixture contains oxygen and nitrogen in the ratio of $1:4$ by weight. The ratio of their number of moleules is :

• A. $1:4$
• B. $1:8$
• C. $7:32$
• D. $3:16$

Answer 1

The correct option is C $7:32$

$w{O}_2:w{N}_2=1:4$

$\frac{w{O}_2}{w{N}_2}=\frac{1}{4}$

$\frac{n{O}_2}{n{N}_2}=\frac{w{O}_2\times Molarmassof{N}_2\times N_A}{w{N}_2\times Molarmassof{O}_2\times N_A}=\frac{1}{4}\times \left(\frac{28}{32}\right)=\frac{7}{32}$

Hence, $n{O}_2:n{N}_2=7:32$