Question

The gas having average speed four times as that of $SO_{2}$ (molecular mass 64) is

• A. He (molecular mass 4)
• B. $O_{2}$ (molecular mass 32)
• C. H₂ (molecular mass 2)
• D. $CH_{4}$ (molecular mass 16)

Answer 1

Answer: (A)

He (molecular mass 4)

Answer 2

$v_{av} \propto \frac{1}{\sqrt{M}}$Ž $\frac{v_{Gas}}{v_{SO_{2}}} = \sqrt{\frac{M_{SO_{2}}}{M_{Gas}}}$ Ž $\frac{4}{1} = \sqrt{\frac{64}{M_{Gas}}}$

Ž $M_{Gas} = 4$ i.e. gas is He.