| A Mixture of 2 moles of helium gas\[\left( atomic\text{ }mass=4u \right)\], and 1 mole of argon gas \[\left( atomic\text{ }mass=40u \right)\] is kept at 300 K in a container. The ratio of their rms speeds |
| \[\left[ \frac{{{V}_{rms}}\,(helium)}{{{V}_{rms}}\,(argon\,)} \right]\] , is close to: [JEE Main 09-Jan-2019 Morning] |
A) 0.32
B) 3.16
C) 2.24
D) 0.45
Correct Answer: B
Solution :
| [b] \[\because \,\,\,\,\,\,{{V}_{rms}}\,=\,\,\sqrt{\frac{3RT}{M}}\] |
| for same temperature |
| \[{{V}_{rms}}\,\propto \,\,\sqrt{\frac{1}{M}}\] |
| \[\Rightarrow \,\,\,\,\,\,\frac{{{V}_{rms}}(He)}{{{V}_{rms}}\,(Ar)}\,\,=\,\,\sqrt{\frac{40}{4}}\,\,\,=\,\,\,\,\sqrt{10}\,\,=\,\,3.16\] |
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