Question

A vessel of volume $0.02m^3$ contains a mixture of hydrogen and helium at ${20}^{\circ }C$ and $2atm$ pressure. The mass of mixture is $5g$. Find the ratio of mass of hydrogen to that of helium in the mixture.

• A. 1:2
• B. 1:3
• C. 2:3
• D. 3:2

Answer 1

The correct option is A 1:2

From ideal gas equation, $PV=nRT$

Here, assume the mass of helium in the mixture is $x$, then the mass of hydrogen is $(5-x)$.

Applying ideal gas law,

$2\times {10}^5\times 0.02=(\frac{5-x}{2}+\frac{x}{4})\times 8.314\times 293$.

$x=3.43$ and $5-x=1.57$.

So, the ratio of hydrogen to helium is 1 : 2.

Hence, option A is correct.