A mixture of hydrogen
Question:

A mixture of hydrogen and oxygen has volume $500 \mathrm{~cm}^{3}$, temperature $300 \mathrm{~K}$, pressure $400 \mathrm{kPa}$ and mass $0.76 \mathrm{~g}$. The ratio of masses of oxygen to hydrogen will be :-

1. $3: 8$

2. $3: 16$

3. $16: 3$

4. $8: 3$

Correct Option: , 3

Solution:

$P V=n R T$

$400 \times 10^{3} \times 500 \times 10^{-6}=n\left(\frac{25}{3}\right)(300)$

$\mathrm{n}=\frac{2}{25}$

$\mathrm{n}=\mathrm{n}_{1}+\mathrm{n}_{2}$

$\frac{2}{25}=\frac{\mathrm{M}_{1}}{2}+\frac{\mathrm{M}_{2}}{32}$

Also $\mathrm{M}_{1}+\mathrm{M}_{2}=0.76 \mathrm{gm}$

$\frac{\mathrm{M}_{2}}{\mathrm{M}_{1}}=\frac{16}{3}$