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Question: Answered & Verified by Expert
At room temperature a diatomic gas is found to have an r.m.s. speed of $1930 \mathrm{~ms}^{-1}$. The gas is:
PhysicsKinetic Theory of GasesJEE MainJEE Main 2014 (12 Apr Online)
Options:
  • A
    $\mathrm{H}_2$
  • B
    $\mathrm{Cl}_2$
  • C
    $\mathrm{O}_2$
  • D
    $\mathrm{F}_2$
Solution:
1324 Upvotes Verified Answer
The correct answer is:
$\mathrm{H}_2$
$$
\begin{aligned}
&\because \quad \mathrm{C}=\sqrt{\frac{3 \mathrm{RT}}{\mathrm{M}}} \\
&\left(1930^2\right)=\frac{3 \times 8.314 \times 300}{\mathrm{M}} \\
&\mathrm{M}=\frac{3 \times 8.314 \times 300}{1930 \times 1930} \approx 2 \times 10^{-3} \mathrm{~kg}
\end{aligned}
$$
The gas is $\mathrm{H}_2$.

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