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Electrochemistry question

2021 · 24 Feb · Shift 1 · Q1

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Electrochemistry
2021 · 24 Feb · Shift 1 · Q1

Electrochemistry question

2021 · 24 Feb · Shift 1 · Q1

JEE MainChemistryElectrochemistryMCQ+4 / −1

The electrode potential of

M^{2+}

/M of 3d-series elements shows positive value for :

A
Zn
B
Fe
C
Cu
D
Co

View written solutionFree

Correct answer: C

We are asked which $3d$ -series element has a positive standard electrode potential for the half-cell:

$M^{2+} + 2e^- \rightarrow M$

This means we need to identify the metal whose standard reduction potential $E^\circ(M^{2+}/M)$ is positive.

Recall the standard reduction potentials of the given metals:

For $\mathrm{Zn^{2+}/Zn}$ : $E^\circ = -0.76\,\text{V}$
For $\mathrm{Fe^{2+}/Fe}$ : $E^\circ = -0.44\,\text{V}$
For $\mathrm{Co^{2+}/Co}$ : $E^\circ = -0.28\,\text{V}$
For $\mathrm{Cu^{2+}/Cu}$ : $E^\circ = +0.34\,\text{V}$

Now evaluate each option:

A: Zn $\rightarrow E^\circ < 0$ ❌
B: Fe $\rightarrow E^\circ < 0$ ❌
C: Cu $\rightarrow E^\circ > 0$ ✅
D: Co $\rightarrow E^\circ < 0$ ❌

Therefore, the only metal among the given options with positive electrode potential is:

$\boxed{\text{Cu}}$

So, the correct option is C.

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