At `400 K`, the root mean square (rms) speed of a gas X (molecular weight = 40) is equal to the most probable speed of gas Y at 60 K. The molecular weight of the gas Y is.

Answer

4

Explanation

`u=sqrt((3RT)/(M))" and "alpha=sqrt((2RT)/(M))`
`u_(X)=sqrt((3RT)/(M_(X)))"and "alpha_(Y)=sqrt((2RT_(Y))/(M_(Y)))`
As `u_(X)=alpha_(Y),:. (3RT_(X))/(M_(X))=(2RT_(Y))/(M_(Y))`
or `M_(Y)=(2)/(3)(T_(Y))/(T_(X))xx M_(X)=(2)/(3)xx(60)/(400)xx40=4`