When `KMnO_(4)` solution is titrated with a solution containing `Fe^(2+)` ion, the indicator used in this titration is

Options

A. Phenolphthalein
B. Methyl orange
C. `K_(3)[Fe(CN)_(6)]`
D. None of these

Explanation

To determine the indicator used in the titration of KMnO₄ with a solution containing Fe²⁺ ions, we can analyze the reaction and the properties of KMnO₄.

### Step-by-Step Solution:

1. **Identify the Reactants**: The two reactants in this titration are potassium permanganate (KMnO₄) and iron(II) ions (Fe²⁺).

2. **Understand the Nature of KMnO₄**: KMnO₄ is a strong oxidizing agent. In acidic medium, it can oxidize Fe²⁺ ions to Fe³⁺ ions.

3. **Reaction Mechanism**: The balanced redox reaction between KMnO₄ and Fe²⁺ in an acidic medium can be represented as:
\[ \text{MnO}_4^- + 5 \text{Fe}^{2+} + 8 \text{H}^+ \rightarrow \text{Mn}^{2+} + 5 \text{Fe}^{3+} + 4 \text{H}_2\text{O} \]
Here, MnO₄⁻ is reduced to Mn²⁺ while Fe²⁺ is oxidized to Fe³⁺.

4. **Color Change During Titration**: KMnO₄ has a deep violet color in solution. As it reacts with Fe²⁺, the color of the solution changes from violet to colorless (or light pink) when all Fe²⁺ ions are oxidized.

5. **Self-Indicator Property**: KMnO₄ itself acts as a self-indicator because the color change (from violet to colorless) indicates the endpoint of the titration. Therefore, no additional indicator is needed.

6. **Conclusion**: Since KMnO₄ serves as its own indicator, the answer to the question is that no additional indicator is required.

### Final Answer:
The indicator used in the titration of KMnO₄ with Fe²⁺ ions is **none** (KMnO₄ acts as a self-indicator).