A mixture of nitrogen and hydrogen gas has density `0.505xx10^(-3)"g cm"^(-3)` at 293 K and 750 mm Hg pressure.
What per cent of the mass is nitrogen?

Explanation

To solve the problem of determining the percentage of nitrogen in a mixture of nitrogen and hydrogen gas with a given density, we can follow these steps:

### Step-by-Step Solution:

1. **Convert Pressure to Atmospheres**:
The pressure given is 750 mm Hg. To convert this to atmospheres (atm), we use the conversion factor \(1 \text{ atm} = 760 \text{ mm Hg}\):
\[
P = \frac{750 \text{ mm Hg}}{760 \text{ mm Hg/atm}} = 0.9868 \text{ atm}
...