One mole of He gas at 0.6 atm takes 40 s to diffuse through a pin hole. Calculate the time required for diffusion of half mole of `CH_(4)` gas at 1.2 atm through the same hole.

Explanation

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

### Step-by-step solution:

1. **Identify the known values:**
- Moles of He (n_He) = 1 mole
- Pressure of He (P_He) = 0.6 atm
- Time taken for He (t_He) = 40 s
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