Question

Equal weights of ethane and hydrogen are mixed in an empty container at ${25}^{o}C$. The fraction of the total pressure exerted by hydrogen is:

• A. $1:2$
• B. $1:1$
• C. $1:16$
• D. $15:16$

Answer 1

The correct option is D $15:16$

Let $xg$ each of hydrogen and ethane are mixed.

The moles of hydrogen and methane are $\frac{x}{2}$ and $\frac{x}{30}$ respectively.

The mole fraction of hydrogen is $=\frac{\frac{x}{2}}{\frac{x}{2}+\frac{x}{30}}=\frac{15}{16}$.

The partial pressure of hydrogen is the product of its mole fraction and total pressure.

Thus $\frac{\text{Partial pressure of}{H}_2}{\text{Total pressure}}=\text{mole fraction of hydrogen}=\frac{15}{16}$.