Q. In the industrial production of which of the following, molecular hydrogen is obtained as a byproduct?

541 158 JEE MainJEE Main 2022Hydrogen Report Error

A

NaOH

64%

B

NaCl

0%

C

Na metal

0%

D

$N a_{2} C O_{3}$

36%

Solution:

Sodium hydroxide is generally prepared commercially by electrolysis of sodium chloride in castner Kellner cell.
at cathode : $N a + e^{-} H g N a -$ amalgum
Anode $: C l^{-} ⟶ \frac{1}{2} C l_{2} + e^{-}$
The $N a$ -amalgam is treated with water to give sodium hydroxide and hydrogen gas :
$2 N a$ (amalgam) $+ H_{2} O \to 2 N a O H + H_{2} + 2 H g$