Question

$X$ mL of $H_2$ effuse through a hole in a container in 5 seconds. The time taken for the effusion of the same volume of the gas specified below under identical conditions is

• A. 10 seconds : He
• B. 20 seconds : $O_2$
• C. 25 seconds : CO
• D. 55 seconds : $CO_2$

Answer 1

Answer: (B)

20 seconds : $O_2$

Answer 2

For effusion of same volume , $\frac{t_1}{t_2} = \sqrt{\frac{M_1}{M_2}}$ This is clearly seen from the options that the Option (B) is correct $\frac{^tH_2}{^tO_2} = \sqrt{\frac{M_{H_2}}{M_{O_2}}} = \sqrt{\frac{2}{32}}$ $\frac{^tH_2}{^tO_2} = \frac{1}{4} ; \frac{5}{^tO_2} = \frac{1}{4}$ or $^tO_2 = 5 \times 4$ = 20 s. $\frac{5}{\sqrt{2}} = \sqrt{\frac{20}{32}} = \frac{5}{\sqrt{2}}$