JEE Main · 2022 · Shift-IIeasyEC-011

In 3d series, the metal having the highest M2+/M standard electrode potential is

Electrochemistry · Class 12 · JEE Main Previous Year Question

Question

In 3d series, the metal having the highest M2+/M\mathrm{M^{2+}/M} standard electrode potential is

Options
  1. a

    Cr

  2. b

    Fe

  3. c

    Cu

  4. d

    Zn

Correct Answerc

Cu

Detailed Solution

Strategy: Within the 3d transition series, most metals have negative reduction potentials (E°\ceM2+/ME°_{\ce{M^{2+}/M}}), meaning they are more reactive than hydrogen. Identify the ex\ception that is less reactive (positive E°).

Analysis: The E° values for the relevant 3d metals are:

  • \ceCr2+/Cr\ce{Cr^{2+}/Cr}: 0.91 V-0.91\ \mathrm{V}
  • \ceFe2+/Fe\ce{Fe^{2+}/Fe}: 0.44 V-0.44\ \mathrm{V}
  • \ceZn2+/Zn\ce{Zn^{2+}/Zn}: 0.76 V-0.76\ \mathrm{V}
  • \ceCu2+/Cu\ce{Cu^{2+}/Cu}: +0.34 V+0.34\ \mathrm{V}

Copper is the only metal in the 3d series with a positive reduction potential, making it the highest among the listed elements.

Answer: (c) Cu\boxed{\text{Answer: (c) Cu}}

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