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)))implies (v_(A))/(t_(A))xx(t_(B))/(v_(B))=sqrt((M_(B))/(M_(B)))implies(10)/(20)=sqrt((M_(B))/(49))`
`implies (1)/(4) =(M_(B))/(49)`
`:. M_(B)=(49)/(4)=12.25`