Electrochemistry Ques 17
17. In electrolysis of $NaCl$, when $Pt$ electrode is taken, then $H_2$ is liberated at cathode while with $Hg$ cathode, it forms sodium amalgam. This is because
[2002]
(a) $Hg$ is more inert than $Pt$
(b) More voltage is required to reduce $H^{+}$at $Hg$ than at $Pt$
(c) $Na$ is dissolved in $Hg$ while it does not dissolve in $Pt$
(d) Conc. of $H^{+}$ions is larger when Pt electrode is taken
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Answer:
Correct Answer: 17.(b)
Solution:
(b) If mercury is used as cathode, $H^{+}$ions are not discharged at mercury cathode because mercury has a high over voltage for hydrogen.
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