If two gases X and Y have their molecules travelling at the velocities in the ratio of `3 : 1`. The ration of their molecular mass `M_(x)//M_(y)` will be

Options

A. `(1)/(9)`
B. 9
C. 3
D. `(1)/(3)`

Answer

B

Explanation

`rprop"velocity"(r_(X))/(r_(Y))=sqrt(M_(Y)/M_(X))`
`(3)/(1)=sqrt(M_(Y)/M_(X))" ""or" " " 9=(M_(Y))/(M_(X))"or"(M_(X))/(M_(Y))=(1)/(9)`