Question

If the four tubes of a car are filled to the same pressure with $N_2,O_2,H_2$ and $He$ separately then which one will be filled first :

• A. $N_2$
• B. $O_2$
• C. $H_2$
• D. $He$

Answer 1

Answer: (C)

$H_2$

According to Graham 's Law of diffusion .

At constant temperature and pressure rate of diffusion of non -reactive gases are inversely proportional to square root of their density or molar mass

$\frac{r_1}{r_2}=\sqrt{\frac{M_2}{M_1}}$

It means gas of higher molar mass will be diffused less.

Order of molar mass

$H_2<N_2<O_2<C{O}_2$

So, order of the rate of diffusion ,

$C{O}_2<O_2<N_2<H_2$

So ,H2 will be fill first.

Hence option C is correct.