A certain gas takes three times as long to effuse out as helium. Its molecular mass will be-

Options

A. 36u
B. 64u
C. 9u
D. 27u

Answer

A

Explanation

`r_(1)/r_(2)=sqrt((M_(2))/(M_(1))) or, (v//t_(1))/(v//t_(2))=sqrt((M_(2))/(M_(1))) or, (t_(2))/(t_(1))=sqrt((M_(2))/(M_(1)))`
or, `(3)/(1)=sqrt((M_(2))/(4u)) or, M=36u`
[`t_(1) and t_(2)` are the times for the diffusion of V mL He and VmL unknown gas respectively. `M_(1)=`Molar mass of He, `M_(2)`=molarr mass of unknown gas].