Kinetic Theory

JEE Main level, single correct, medium

63 of 168

Question 63 of 168

A mixture of 2 moles of helium gas (atomic mass = 4u) ,, and 1 mole of argon gas (atomic mass = 40 u) is kept at 300K300K in a container. The ratio of their rms speeds [Vrms(helium)Vrms(argon)],\left[\dfrac{{V}_{rms}\left(helium\right)}{{V}_{rms}(argon)}\right], is close to:

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Answer: (D) 3.163.16

VRMS=3RTM{V}_{RMS}=\sqrt{\dfrac{3RT}{M}}

∴(VRMS)He(VRMS)Ar=MArMHe=404=10=3.16∴\dfrac{{({V}_{RMS})}_{He}}{{({V}_{RMS})}_{Ar}}=\sqrt{\dfrac{{M}_{Ar}}{{M}_{He}}}=\sqrt{\dfrac{40}{4}}=\sqrt{10}=3.16

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