Question

Equal masses of Methane and Hydrogen are mixed in an empty container at ${25}^{\circ }C$. The fraction of the total pressure exerted by hydrogen is :

• A. $\frac{1}{2}$
• B. $\frac{8}{9}$
• C. $\frac{1}{9}$
• D. $\frac{16}{17}$

Answer 1

The correct option is B $\frac{8}{9}$

The molar masses of methane and hydrogen are 16 g/mol and 2 g/mol respectively.
Assume that 16 g each of methane and hydrogen are present.

The number of moles of methane and hydrogen are $\frac{16}{16}=1$ and $\frac{16}{2}=8$ respectively.

The mole fraction of hydrogen is $\frac{8}{8+1}=\frac{8}{9}$. This is also equal to the fraction of the total pressure exerted by hydrogen.

So, the correct option is $B$