Question

The rate of diffusion of methane at a given temperature is twice of a gas X. The molar mass of the gas X is:

• A. 64
• B. 32
• C. 16
• D. 8
• E. 4

Answer 1

Answer: (A)

Relation between rate of diffusions and molar masses of the gases X and
$C{H}_4$ is $\frac{r_x}{r_{C{H}_4}}=\sqrt{\frac{M_{C{H}_4}}{M_x}}$
Let the rate of diffusion of gas
$X=a$ $\therefore$
$\frac{a}{2a}=\sqrt{\frac{16}{M_X}}$
( $\because$ $C{H}_4=12.4=16$ )
$\therefore$ $\frac{1}{2}=\sqrt{\frac{16}{M_X}}$
$\therefore$ $M_X=16\times 4=64$
So, the molar mass of gas X is 64.