Question

A straight glass tube has two inlet x and y at two ends. The length of the tube is 400 cm. $H_2$ gas enters through inlet x and travels 100 cm then $O_2$ gas enters through y inlet. First drop of water appears at a point P inside the tube. Find the distance of P from x.

• A. 240 cm
• B. 340 cm
• C. 60 cm
• D. 160 cm

Answer 1

The correct option is B 340 cm


$Diffustion\propto \frac{1}{\sqrt{m}}\frac{r_{H_2}}{r_{O_2}}=\sqrt{\frac{M_{O_2}}{M_{H_2}}}=\sqrt{\frac{32}{2}}=\sqrt{\frac{16}{1}}=\frac{4}{1}{r}_{H_2}:r_{O_2}=4:1$
So $H_2$ gas will travel faster than $O_2$ gas so $H_2$ gas travel more distance.
$x=300\times \frac{4}{5}=240cm$
But $H_2$ gas travel first 100 cm alone so first drop of water will form at 240 + 100 = 340 cm.