Question

A gaseous mixture contains oxygen and nitrogen in the ratio $1:4$ by weight. Therefore, the ratio of the number of molecules is :

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

Answer 1

Answer: (C)

$7:32$

Molar ratio of oxygen ($O_2$) : nitrogen ($N_2$) $=\frac{1}{32}:\frac{4}{28}$
$\therefore$ Ratio of their molecules $=\frac{N_A}{32}:\frac{4N_A}{28}\Rightarrow 7:32$