Question

Two vessels $A$ and $B$ having equal volume contain equal masses of hydrogen in $A$ and helium in $B$ at $300K$. Then, mark the correct statement.

• A. The pressure exerted by hydrogen is half that exerted by helium
• B. The pressure exerted by hydrogen is equal to that exerted by helium
• C. Average KE of the molecule of hydrogen is half the average KE of the molecules of helium
• D. The pressure exerted by hydrogen is twice that exerted by helium

Answer 1

Answer: (D)

$pV=nRT$
$p_{H_2}=\frac{m}{M_{H_2}}\cdot \frac{RT}{V}$
$p_{He}=\frac{m}{M_{He}}\cdot \frac{RT}{V}$
$\therefore \frac{P_{H_2}}{P_{He}}=\frac{M_{He}}{M_{H_2}}$
$=\frac{4\times 10^{-3}}{2\times 10^{-3}}=2$
$\Rightarrow p_{H_2}=2P_{He}$