Two gases $A$ and $B$ having the same volume diffuse through a porous partition in 20 and 10 seconds…
Two gases $A$ and $B$ having the same volume diffuse through a porous partition in 20 and 10 seconds respectively. The molecular mass of $A$ is $49 \mathrm{u}$. Molecular mass of $B$ will be
$12.25 \mathrm{u}$
$6.50 \mathrm{u}$
$25.00 \mathrm{u}$
$50.00 \mathrm{u}$
Solution
$\frac{r_A}{r_B}=\sqrt{\frac{M_B}{M_A}}$
or $\frac{V_A}{t_A} \times \frac{t_B}{V_B}=\sqrt{\frac{M_B}{M_A}}$
or $\quad \frac{10}{20}=\sqrt{\frac{M_B}{49}}$
or $\quad \frac{1}{4}=\frac{M_B}{49}$
$\therefore \quad M_B=\frac{49}{4}=12.25 \mathrm{u}$.