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

The correct option is D 15:16
Let $30g$ of both be mixed.

Moles of $H_2=\frac{30}{2}=15$

Moles of $C_2{H}_6=\frac{30}{30}=1$

Mole fraction of $H_2=\frac{15}{1+15}=\frac{15}{16}$

which is also the fraction of total pressure executed by $H_2$.

So, the correct option is $D$