Kinetic Theory

JEE Main level, single correct, medium

24 of 168

Question 24 of 168

The ratio of vapour densities of two gases at the same temperature is 425\frac{4}{25}, then the ratio of r.m.s. velocities will be:

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Answer: (C) 52\frac{5}{2}

(Vapor density) =( Molar mass 2)=\left(\frac{\text { Molar mass }}{2}\right), I.e, vd=M2v d=\frac{M}{2}
vrms=3RTMv2v1=M1M2=254=52\begin{aligned} & v_{\mathrm{rms}}=\sqrt{\frac{3 R T}{M}} \\ & \frac{v_2}{v_1}=\sqrt{\frac{M_1}{M_2}}=\sqrt{\frac{25}{4}}=\frac{5}{2}\end{aligned}

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