If mercury is used as a cathode during the electrolysis of an aqueous NaCl solution, the ions discha — Electrochemistry Chemistry Question

💡 Solution & Explanation

Normally, in an aqueous solution, $H^+$ is reduced before $Na^+$. However, hydrogen gas has a very high overvoltage on a mercury cathode, making its reduction kinetically unfavorable. Consequently, $Na^+$ ions are preferentially discharged to form sodium amalgam (Na-Hg). Therefore, correct answer is B.