`50 mL` of each gas `A` and of gas `B` takes `150 and 200` seconds respectively for effusing through a pin hole under the similar conditon. If molecular mass of gas `B` is `36`, then the molecular mass of gas `A` will be

Options

A. 96
B. 128
C. 32
D. 64

Explanation

To solve the problem, we will use Graham's law of effusion, which states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass.

### Step-by-Step Solution:

1. **Identify Given Values**:
- Volume of gas A (VA) = 50 mL
- Volume of gas B (VB) = 50 mL
- Time taken for gas A (TA) = 150 seconds
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