Question

Which one of the following gases would have the highest $RMS$ velocity at ${25}^{\circ }C$?

• A. Oxygen
• B. Carbon dioxide
• C. Sulphur dioxide
• D. Carbon monoxide

Answer 1

The correct option is D Carbon monoxide

Carbon monoxide would have the highest $RMS$ velocity at ${25}^{\circ }C$ as it has lowest molar mass (28 $g/mol$).

$V_{\text{rms}}=\sqrt{\frac{3RT}{M}}$

$RMS$ speed is inversely proportional to the square root of molar mass.

Higher is the molar mass of the substance, lower is the root mean square velocity of it and vice versa.

Hence, the correct option is $\text{D}$