Question

A certain gas effuses out of two different vessels $A$ and $B$. $A$ has a circular orifice while $B$ has a square orifice of length equal to the radius of the orifice of vessel $A$. The ratio of rate of diffusion of the gas from vessel $A$ to that from vessel $B$ is

• A. $\pi :1$
• B. $1:\pi$
• C. $1:1$
• D. $3:2$

Answer 1

The correct option is A $\pi :1$

Let the radius of circular orifice $=r$
So the the side length of square orifice $=r$ (given)
Rate of effusion $\propto$ Area of cross section
$\therefore \frac{r_A}{r_B}=\frac{A_A}{A_B}=\frac{\pi r^2}{r^2}=\frac{\pi }{1}$