Assertion : `E^@` value of `Mn^(3+) | Mn^(2+)` is more positive than for `Cr^(3+)| Cr^(2+)`.
Reason `Cr^(3+)` is more stable than `Cr^(2+)` but `Mn^(3+)` is less stable than `Mn^(2+)`.

Options

A. Assertion and reason both are correct statements and reason is correct explanation for assertion.
B. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
C. Assertion is correct statement but reason is wrong statement.
D. Assertion is wrong statement but reason is correct statement

Answer

To solve the assertion-reason question, we need to analyze both the assertion and the reason step by step.

### Step 1: Analyze the Assertion
**Assertion**: The \(E^\circ\) value of \(Mn^{3+} | Mn^{2+}\) is more positive than for \(Cr^{3+} | Cr^{2+}\).

- **Understanding \(E^\circ\) Values**: The standard electrode potential (\(E^\circ\)) indicates the tendency of a species to gain electrons (be reduced). A more positive \(E^\circ\) value means a greater tendency to be reduced.
- **Comparing \(Mn^{3+}\) and \(Mn^{2+}\)**:
- Manganese in the \(Mn^{2+}\) state has the electron configuration of \(3d^5\), which is a half-filled configuration and thus more stable.
- \(Mn^{3+}\) has the configuration \(3d^4\), which is less stable than \(Mn^{2+}\).
- Therefore, the conversion from \(Mn^{3+}\) to \(Mn^{2+}\) is favorable, leading to a more positive \(E^\circ\) value.

- **Comparing \(Cr^{3+}\) and \(Cr^{2+}\)**:
- Chromium in the \(Cr^{2+}\) state has the configuration \(3d^4\) and \(Cr^{3+}\) has \(3d^3\).
- \(Cr^{3+}\) is more stable than \(Cr^{2+}\) due to lesser electron-electron repulsion in the \(3d\) orbitals.
- Thus, the conversion from \(Cr^{3+}\) to \(Cr^{2+}\) is less favorable, leading to a less positive \(E^\circ\) value.

**Conclusion for Assertion**: The assertion is **true** because \(Mn^{3+} | Mn^{2+}\) has a more positive \(E^\circ\) value compared to \(Cr^{3+} | Cr^{2+}\).

### Step 2: Analyze the Reason
**Reason**: \(Cr^{3+}\) is more stable than \(Cr^{2+}\) but \(Mn^{3+}\) is less stable than \(Mn^{2+}\).

- **Stability of \(Cr^{3+}\) vs \(Cr^{2+}\)**:
- \(Cr^{3+}\) has a \(3d^3\) configuration, which is stable due to reduced electron repulsion.
- \(Cr^{2+}\) has a \(3d^4\) configuration, which is less stable due to increased electron repulsion.

- **Stability of \(Mn^{3+}\) vs \(Mn^{2+}\)**:
- \(Mn^{2+}\) has a \(3d^5\) configuration, which is stable (half-filled).
- \(Mn^{3+}\) has a \(3d^4\) configuration, which is less stable than \(Mn^{2+}\).

**Conclusion for Reason**: The reason is also **true** as it correctly describes the stability of the oxidation states of chromium and manganese.

### Final Conclusion
Both the assertion and reason are true, and the reason correctly explains the assertion. Therefore, the answer is that both the assertion and reason are true, and the reason is the correct explanation for the assertion.