`1 L` of a gaseous mixture is effused in `5 min 11s`, while `1 L` of oxygen takes `10 min`. The gaseous mixture contains methane and hydrogen. Calculate
(`a`) The density of gaseous mixture.
(`b`) The percentage by volume of each gas in mixture.

Explanation

To solve the problem step by step, we will first calculate the density of the gaseous mixture and then determine the percentage by volume of each gas in the mixture.

### Step 1: Convert Time to Seconds
We need to convert the time taken for effusion of the gaseous mixture and oxygen into seconds.

- Time taken for the gaseous mixture:
\[
5 \text{ min } 11 \text{ sec} = 5 \times 60 + 11 = 311 \text{ seconds}
...