A mixture of `50mL` of `H_(2)` and `50mL` of `O_(2)` is allowed to effuse through an effusiometer till the residual gas occupies `90 mL`. What is the composition of (`a`) effused gas, (`b`) the residual gas?

Explanation

To solve the problem, we need to determine the composition of the effused gas and the residual gas after allowing a mixture of 50 mL of hydrogen (H₂) and 50 mL of oxygen (O₂) to effuse until the residual gas occupies 90 mL.

### Step-by-Step Solution:

1. **Initial Setup**:
- We start with a total volume of gases:
\[
V_{total} = 50 \, \text{mL} \, H_2 + 50 \, \text{mL} \, O_2 = 100 \, \text{mL}
...