Reduction of the metal centre in aqueous permanganate ion involves

Options

A. 3 electrons in neutral medium
B. 5 electrons in neutral medium
C. 3 electrons in alkaline medium
D. 5 electrons in acidic medium

Explanation

To solve the question regarding the reduction of the metal center in aqueous permanganate ion, we will analyze the reactions in different media: acidic, neutral, and alkaline.

### Step-by-Step Solution:

1. **Identify the Permanganate Ion Reaction in Acidic Medium:**
- The reaction of permanganate ion (MnO₄⁻) in acidic medium involves the following equation:
\[ \text{MnO}_4^{-} + 8\text{H}^+ + 5\text{e}^- \rightarrow \text{Mn}^{2+} + 4\text{H}_2\text{O} \]
- In this reaction, 5 electrons are required for the reduction of MnO₄⁻ to Mn²⁺.

**Hint:** Remember that in acidic conditions, MnO₄⁻ is reduced to Mn²⁺, and you need to balance the charges and atoms.

2. **Identify the Permanganate Ion Reaction in Neutral Medium:**
- In neutral medium, the reaction is:
\[ \text{MnO}_4^{-} + 2\text{H}_2\text{O} + 3\text{e}^- \rightarrow \text{MnO}_2 + 4\text{OH}^- \]
- Here, 3 electrons are involved in the reduction of MnO₄⁻ to MnO₂.

**Hint:** In neutral conditions, water acts as a reactant, and hydroxide ions are produced.

3. **Identify the Permanganate Ion Reaction in Alkaline Medium:**
- In alkaline medium, the reaction is:
\[ \text{MnO}_4^{-} + \text{e}^- \rightarrow \text{MnO}_4^{2-} \]
- This shows that only 1 electron is involved in the reduction of MnO₄⁻ to MnO₄²⁻.

**Hint:** In alkaline conditions, the reduction is less extensive compared to acidic conditions.

4. **Summarize the Findings:**
- In acidic medium: 5 electrons
- In neutral medium: 3 electrons
- In alkaline medium: 1 electron

5. **Evaluate the Options:**
- Based on the findings:
- **Option 1:** 3 electrons in neutral media - **Correct**
- **Option 2:** 5 electrons in neutral media - **Incorrect**
- **Option 3:** 3 electrons in alkaline media - **Incorrect**
- **Option 4:** 5 electrons in acidic medium - **Correct**

### Final Answer:
The correct options are **1 and 4**.