Question

Two vessels $A$ and $B$ having equal volume contain equal masses of hydrogen in $A$ and helium in $B$ at $300 \,K$. 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)

$p V=n R T$
$p_{H_{2}}=\frac{m}{M_{H_{2}}} \cdot \frac{R T}{V}$
$p_{H e}=\frac{m}{M_{H e}} \cdot \frac{R T}{V}$
$\therefore \frac{P_{H_{2}}}{P_{H e}}=\frac{M_{H e}}{M_{H_{2}}} $
$=\frac{4 \times 10^{-3}}{2 \times 10^{-3}}=2$
$\Rightarrow p_{H_{2}}=2 P_{H e}$