Question

At room temperature $\left({27}^{\circ }C\right)$ the rms speed of the molecules of a certain diatomic gas is found to be $1920m{s}^{-1}$. The gas is

• A. H₂
• B. F₂
• C. O₂
• D. CI₂

Answer 1

The correct option is A

H₂

We know that $v_{rms}=\sqrt{\frac{3RT}{M}}$ which gives

$M=\frac{3RT}{v_{rms}^2}=\frac{3\times 8.3\times 300}{(1920{)}^2}$

$=2\times {10}^{-3}kg=2g$

Since $M=2$, the gas is hydrogen

The correct choice is (a)