The correct statements about \(Cr^{2+}\) and \(Mn^{3+}\) are: (atomic number of Cr=24 and Mn = 25

(A) \(Cr^{2+}\) is a reducing agent

(B) \(Mn^{3+}\) is an oxidising agent

(C) Both \(Cr^{2+}\) and  \(Mn^{3+}\) exhibit \(d^4\) electronic configuration

(D) When \(Cr^{2+}\) is used as reducing agent chromium ion attains \(d^5\) electronic configuration

Choose the correct answer from the options given below:

(A), (B), (C) only

The correct answer is option 2. (A), (B), (C) only.

Let us delve into each statement in detail:

Statement (A): \(Cr^{2+}\) is a reducing agent

Chromium has the atomic number 24, and its neutral atomic configuration is \( [Ar] 3d^5 4s^1 \). When it loses two electrons to form \(Cr^{2+}\), the configuration becomes \( [Ar] 3d^4 \). \(Cr^{2+}\) can be oxidized to \(Cr^{3+}\). The electronic configuration of \(Cr^{3+}\) is \( [Ar] 3d^3 \). \(Cr^{2+}\) acts as a reducing agent because it can donate electrons to another species (i.e., it gets oxidized to \(Cr^{3+}\)). The reduction of \(Cr^{2+}\) leads to an increase in its oxidation state, thereby demonstrating its role as a reducing agent.

Conclusion: This statement is correct.

Statement (B): \(Mn^{3+}\) is an oxidizing agent

Manganese has the atomic number 25, and its neutral atomic configuration is \( [Ar] 3d^5 4s^2 \). For \(Mn^{3+}\), the configuration is \( [Ar] 3d^4 \).  \(Mn^{3+}\) is a relatively strong oxidizing agent because it can be reduced to \(Mn^{2+}\), which has the electronic configuration \( [Ar] 3d^5 \). The \(Mn^{2+}\) ion is more stable compared to \(Mn^{3+}\), so \(Mn^{3+}\) can readily accept electrons to achieve the more stable \(Mn^{2+}\) state.

Conclusion: This statement is correct.

Statement (C): Both \(Cr^{2+}\) and \(Mn^{3+}\) exhibit \(d^4\) electronic configuration

Electronic Configuration of \(Cr^{2+}\): As discussed above, \(Cr^{2+}\) has the configuration \( [Ar] 3d^4 \).

Electronic Configuration of \(Mn^{3+}\): Similarly, \(Mn^{3+}\) also has the configuration \( [Ar] 3d^4 \).

Both ions indeed have a \(d^4\) configuration.

Conclusion: This statement is correct.

Statement (D): When \(Cr^{2+}\) is used as a reducing agent, the chromium ion attains \(d^5\) electronic configuratio

When \(Cr^{2+}\) (with \( [Ar] 3d^4 \)) is used as a reducing agent, it gets oxidized to \(Cr^{3+}\) (with \( [Ar] 3d^3 \)). The \(d^5\) configuration is actually achieved when \(Cr^{3+}\) is reduced to \(Cr^{2+}\) in some reactions, but not by the oxidation of \(Cr^{2+}\). In the reduction context, \(Cr^{2+}\) would not result in a \(d^5\) configuration; instead, it would be \(Cr^{3+}\) if it's the reduced form.

Conclusion: This statement is incorrect.

Therefore, the correct answer is: (2) (A), (B), (C) only