Question

Assertion :The electrolysis of NaCl solution gives $H_2$ (g) at cathode and $C{l}_2$ (g) at anode. Reason: $C{l}_2$ has higher oxidation potential than $H_{2}O$.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is C Assertion is correct but Reason is incorrect

The aqueous solution of sodium chloride contains $N{a}^{+},C{l}^{-},H^{+}andO{H}^{-}$ ions due to ionization of water.

When the potential difference is established across the solution, $N{a}^{+}$ and $H^{+}$ ions move toward the cathode and $C{l}^{-}$ and $O{H}^{-}$ ions move towards the anode.

At cathode, $H^{+}$ ion is discharge in preference to $N{a}^{+}$ as discharge potential of $H^{+}$ ion is lower than $N{a}^{+}$ ion.

At anode, $C{l}^{-}$ ion is discharged in preference to $O{H}^{-}$ ion.

$NaCl\rightleftharpoons N{a}^{+}+C{l}^{-}$

$H_{2}O\rightleftharpoons H^{+}+O{H}^{-}$

At cathode: $H^{+}+e^{-}\to H$

$2H\to H_2$

At anode: $C{l}^{-}\to Cl+e^{-}$

$2Cl\to C{l}_2$

Therefore, the assertion is correct but the given reason is incorrect.

Hence, the correct option is (C).