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AP EAMCET · Chemistry · d and f Block Elements

The correct statement about \(\mathrm{Cr}^{2+}\) and \(\mathrm{Mn}^{3+}\) among the following is (Given, atomic numbers of \(\mathrm{Cr}=24\) and \(\mathrm{Mn}=25\) )

  1. A \(\mathrm{Cr}^{2+}\) is a reducing agent
  2. B \(\mathrm{Mn}^{3+}\) is a reducing agent
  3. C Both \(\mathrm{Cr}^{2+}\) and \(\mathrm{Mn}^{3+}\) exhibit \(d^5\) outer electronic configuration
  4. D When \(\mathrm{Cr}^{2+}\) is used as reducing agent, it attains \(d^5\) configuration
Verified Solution

Answer & Solution

Correct Answer

(C) Both \(\mathrm{Cr}^{2+}\) and \(\mathrm{Mn}^{3+}\) exhibit \(d^5\) outer electronic configuration

Step-by-step Solution

Detailed explanation

\(\begin{aligned} \mathrm{Cr}^{2+} & \Rightarrow[\mathrm{Ar}] 3 d^4, E_{\mathrm{Cr}^{3+} / \mathrm{Cr}^{2+}}^{\circ}=-0.41 \mathrm{~V} \\ \mathrm{Mn}^{3+} & \Rightarrow[\mathrm{Ar}] 3 d^3, E_{\mathrm{Mn}^{3+} / \mathrm{Mn}^{2+}}^0=+1.51 \mathrm{~V} \end{aligned}\) So, reducing…