Question

A mixture of two gases X and Y is enclosed, at constant temperature. The relative molecular mass of X, which is diatomic, is 8 times that of Y which is monoatomic. What is the ratio of the r.m.s. speed of molecules of Y to that of molecules of X ?

• A. 2
• B. $2\sqrt{2}$
• C. 4
• D. 8

Answer 1

Answer: (B)

$2\sqrt{2}$

Answer 2

$\frac{v_{x}}{v_{y}} = \sqrt{\frac{m_{y}}{m_{x}}} = \sqrt{\frac{m_{y}}{8m_{y}}} \Rightarrow \frac{v_{y}}{v_{x}} = 2\sqrt{2}$