Question

Assertion :If an aqueous solution of $NaCl$ is electrolysed, the product obtained at the cathode is $H_2$ gas and not $Na$. Reason: Gases are liberated faster than the metals.

• 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

Electrolysis of aqueous $NaCl$.

$NaC{l}_{\left(s\right)}\rightleftharpoons N{a}_{\left(aq\right)}^{+}+C{l}_{\left(aq\right)}^{⊝}$.

$H_2{O}_{\left(l\right)}\rightleftharpoons H_{\left(aq\right)}^{⊝}+O{H}_{\left(aq\right)}^{⊝}$.

At Cathode:-

Hydrogen reduction takes place in preference to $N{a}^{+}$ as reduction potential of $N{a}^{+}$ is less than Hydrogen.

$\therefore 2H^{+}+2e\rightleftharpoons H_{2\left(g\right)}$.

At Anode:-

Chlorine gas gets oxidized at anode in preference to $O^{⊝}H$ because it requires over potential for oxidation.

$\therefore 2C{l}^{⊝}\rightleftharpoons C{l}_{2\left(g\right)}+2e$

$\therefore$ Reason is incorrect.