1) A mixture of 2 moles of helium gas (atomic mass = 4 amu) and 1 mole of argon gas (atomic mass=40amu) is kept at 300K in a container. The ratio of the rms speeds $\left(\frac{v_{rms}(helium)}{v_{rms}(argon)}\right)is$ A) 0.32 B) 0.45 C) 2.24 D) 3.16 Answer: Option DExplanation:$ v_{rms}=\sqrt{\frac{3RT}{M}} $ or $V_{rms}\propto \frac{1}{\sqrt{M}}$ $\therefore$ $ \frac{( v_{rms})_{He}}{( v_{rms})_{Ar}}=\sqrt{\frac{M_{Ar}}{M_{He}}}=\sqrt{\frac{40}{4}}=\sqrt{10}\approx3.16$
