Two gases `A` and `B` having the same volume diffuse through a porous partition in `20` and `10` seconds respectively. The molar mass of `A` is `49 u`. Molar mass of `B` will be

Options

A. `25.00 u`
B. `50.00 u`
C. `12.25 u`
D. `6.50 u`

Answer

C

Explanation

`(r_(A))/(r_(B))=sqrt((M_(B))/(M_(A)))`
`(VA)/(t_(A))xx(t_(B))/(V_(B))=sqrt((M_(B))/(M_(A)))`
`(10)/(20)=sqrt((M_(B))/(49))`
`(1)/(4)=(M_(B))/(49) :. M_(B)= (49)/(4)= 12.25 u`