On reaction of moist `SO_(2)` with potassium permangnate (Acidic) which is correctly observed?

Options

A. Colour of `KMnO_(4)` is decolourised
B. `SO_(2)` is oxidised to `SO_(3)`
C. `MnO_(4)^(-)` is reduced to `MnO_(2)`
D. All of these

Answer

To solve the question regarding the reaction of moist SO₂ with potassium permanganate (KMnO₄) in an acidic medium, we can follow these steps:

### Step 1: Understand the Reactants
- **Moist SO₂**: Sulfur dioxide (SO₂) is a gas that can act as a reducing agent.
- **Potassium Permanganate (KMnO₄)**: This is a strong oxidizing agent, and in acidic conditions, it is purple in color due to the presence of MnO₄⁻ ions.

**Hint**: Identify the properties of the reactants involved in the reaction.

### Step 2: Reaction Conditions
- The reaction takes place in an acidic medium, which is important for the reduction of KMnO₄.

**Hint**: Remember that the acidity of the medium can influence the outcome of redox reactions.

### Step 3: Write the Balanced Reaction
The balanced chemical equation for the reaction of moist SO₂ with KMnO₄ in acidic medium is:
\[ 5 \text{SO}_2 + 2 \text{KMnO}_4 + 2 \text{H}_2\text{O} \rightarrow 5 \text{SO}_4^{2-} + 4 \text{H}^+ + 2 \text{Mn}^{2+} \]

**Hint**: Balancing the equation helps in understanding the stoichiometry of the reaction.

### Step 4: Identify the Changes in Oxidation States
- **SO₂** is oxidized to **SO₄²⁻**.
- **MnO₄⁻** is reduced to **Mn²⁺**.

**Hint**: Determine the oxidation states of sulfur and manganese to see how they change during the reaction.

### Step 5: Color Change Observation
- The purple color of KMnO₄ (due to MnO₄⁻) is decolorized as it gets reduced to Mn²⁺, which is typically light pink or colorless in dilute solutions.

**Hint**: Pay attention to the visual changes in the reaction, as they can indicate the progress of the reaction.

### Step 6: Conclusion
Based on the observations:
1. The color of KMnO₄ is decolorized.
2. SO₂ is oxidized to SO₄²⁻.
3. MnO₄⁻ is reduced to Mn²⁺.

Thus, the correct observation from the reaction is that the color of KMnO₄ is decolorized.

**Final Answer**: The color of KMnO₄ is decolorized.