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JEE Main 20204 SeptemberMorning Shift

Exam: JEE Main
Year: 2020
Date: 4 September
Shift: Morning Shift
Subject: Chemistry
Chapter: Electrochemistry

JEE Main 2020 · 4 September · Morning Shift · Chemistry · Electrochemistry

E _ Cu ^ 2 + | Cu ^ 0 = + 0 .34 V E _ Zn ^ 2 + | Zn ^ 0 = - 0 .76 V...

E _ Cu ^ 2 + | Cu ^ 0 = + 0 .34 V E _ Zn ^ 2 + | Zn ^ 0 = - 0 .76 V Identify the incorrect statement from the options

{E}_{{Cu}^{2 +} | Cu}^{0} = + 0 .34 V

{E}_{{Zn}^{2 +} | Zn}^{0} = - 0 .76 V

Identify the incorrect statement from the options below for the above cell:

Options

AIf ${E}_{ext} > 1 .1 V, {e}^{–}$ flow from $Cu$ to $Zn$
BIf ${E}_{ext} > 1 .1 V, Zn$ dissolves at $Zn$ electrode and $Cu$ deposits at $Cu$ electrode
CIf ${E}_{ext} < 1 .1 V, Zn$ dissolves at anode and $Cu$ deposits at cathode
DIf ${E}_{ext} = 1 .1 V,$ no flow of ${e}^{–}$ or current occurs

Correct answer

B. If ${E}_{ext} > 1 .1 V, Zn$ dissolves at $Zn$ electrode and $Cu$ deposits at $Cu$ electrode

Step-by-step solution

${E}_{cell}^{∘} = {E}_{{Cu}^{2 +}\left|Cu\right\}^{∘} - {E}_{{Zn}^{2 +}\left|Zn\right\}^{∘} = 1 .1 V$

So If $E = 1 .1 V$ no electron will flow

At $E > 1 . 1V$ cell act as electrolytic cell and electron will flow from $Cu$ to $Zn$ .

At $E < 1 . 1V$ cell act as electrochemical so $Zn$ dissolve and $Cu$ deposit.

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