Q92 / 100 · BITSAT 2023 (Memory Based Paper 2) · Physics
A flask contains hydrogen and oxygen in the ratio of $2: 1$ by mass at temperature $27^{\circ} \mathrm{C}$. The ratio of average kinetic energy per molecule of hydrogen and oxygen respectively is :
- A
2 : 1 - Correct answerB
1 : 1 - C
1 : 4 - D
4 : 1
Solution
Average kinetic energy for diatomic gases
$\begin{aligned}<br />& \mathrm{K}_{\mathrm{av}}=\frac{5}{2} \mathrm{kT} \\<br />& \therefore \frac{\left(\mathrm{K}_{\mathrm{av}}\right)_{\mathrm{H}}}{\left(\mathrm{K}_{\mathrm{av}}\right)_{\mathrm{O}}}=\frac{(27+273)}{(27+273)}=1<br />\end{aligned}$
$\begin{aligned}<br />& \mathrm{K}_{\mathrm{av}}=\frac{5}{2} \mathrm{kT} \\<br />& \therefore \frac{\left(\mathrm{K}_{\mathrm{av}}\right)_{\mathrm{H}}}{\left(\mathrm{K}_{\mathrm{av}}\right)_{\mathrm{O}}}=\frac{(27+273)}{(27+273)}=1<br />\end{aligned}$
Hence, the correct answer is option: 'B'.