Question

If both oxygen and helium gases are at the same temperature, the rate of diffusion of $O_2$ is very close to:

• A. 4 times that of He
• B. 2 times that of He
• C. 0.35 times that of He
• D. 8 times that of He

Answer 1

Answer: (C)

According to Grahams law of diffusion
$\frac{r_{O_2}}{r_{He}}=\sqrt{\frac{M_{He}}{M_{O_2}}}$
or $=\sqrt{\frac{4}{32}}=\frac{1}{2.83}$
$\therefore r_{O_2}=0.35r_{He}$