Q. At $27℃,$ 500 mL of helium diffuses in 30 min. What is the time (in hours) taken for 1000 mL of ${SO}_{2}$ to diffuse under same experimental conditions?
A) 240
B) 3
C) 2
D) 4
Explanation
(d)
Given, $r_{He} = \frac{500}{30}\ mL/min.$
$r_{{SO}_{2}} = \frac{1000}{t}\ mL/min$
$M_{He} = 4$
$M_{{SO}_{2}} = 64$
From Graham’s law
$\frac{r_{He}}{r_{{SO}_{2}}} = \sqrt{\frac{M_{{SO}_{2}}}{M_{He}}}$
$\frac{500}{30} \times \frac{t}{1000} = \sqrt{\frac{64}{4}}$
$\frac{t}{60} = 4$
$t = 240\ min = 4\ h$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.