Question

0.5 mole of each of $H_{2}$, $SO_{2}$ and $CH_{4}$ are kept in a container. A hole was made in the container. After 3 h, the order of partial pressures in the container will be

• A. $pSO_{2}>pH_{2}>pCH_{4}$
• B. $pSO_{2}>pCH_{4}>pH_{2}$
• C. $pH_{2}>pSO_{2}>pCH_{4}$
• D. $pH_{2}>pCH_{4}>pSO_{2}$

Hint:

Heavier gases diffuse slower and remain in the container longer.

Answer 1

The Correct Option is B

Step 1: Graham's Law
Rate of diffusion $\propto \frac{1}{\sqrt{\text{Molecular Mass}}}$.
Step 2: Diffusion Order
Masses: $H_{2}(2)<CH_{4}(16)<SO_{2}(64)$. Order of diffusion: $H_{2}>CH_{4}>SO_{2}$.
Step 3: Remaining Gas
The gas that diffuses fastest will have the lowest remaining amount and partial pressure. Order of remaining amount/pressure: $SO_{2}>CH_{4}>H_{2}$.
Final Answer: (b)