Question

The gaseous mixture contains oxygen and nitrogen in the ratio of $1:8$ by mass. The ratio of their respective number of molecules $(N_{O_2}:N_{H_2})$ is

• A. $1:8$
• B. $1:1$
• C. $7:64$
• D. $1:2$

Answer 1

The correct option is C $7:64$

Mass ratio equals $(m_{O_2}:m_{N_2})=1/8$
Mole ratio equals $(n_{O_2}:n_{N_2})=\left(1/32\right)/\left(8/28\right)=7/64$
$\therefore$ molecules ratio equals $(N_{O_2}:N_{N_2})=7/64$