b
$\mathrm{V}_{\mathrm{rms}} =\sqrt{\frac{3 \mathrm{RT}}{\mathrm{M}_{\mathrm{w}}}}$
$\Rightarrow \frac{\mathrm{V}_{\mathrm{O}_2}}{\mathrm{~V}_{\mathrm{He}}}$ $=\sqrt{\frac{\mathrm{M}_{\mathrm{w}, \mathrm{He}}}{\mathrm{M}_{\mathrm{w}, \mathrm{O}_2}}}$
$=\sqrt{\frac{4}{32}}=\frac{1}{2 \sqrt{2}}$
$\frac{\mathrm{V}_{\mathrm{He}}}{\mathrm{V}_{\mathrm{O}_2}} =\frac{2 \sqrt{2}}{1}$