Which of the following examples does not represent disproportionation ?

Options

A. `MnO_(2)+4HClrarrMnCl_(2)+Cl_(2)+2H_(2)O`
B. `2H_(2)O_(2)rarr2H_(2)O+O_(2)`
C. `4KClO_(3)rarr3KCiO_(4)+KCl`
D. `3Cl_(2)+6NaOHrarr5NaCl+NaClO_(3)+3H_(2)O`

Explanation

To determine which of the given examples does not represent a disproportionation reaction, we first need to understand what a disproportionation reaction is. A disproportionation reaction is a specific type of redox reaction where the same element undergoes both oxidation and reduction simultaneously, resulting in different oxidation states.

### Step-by-Step Solution:

1. **Identify the Definition of Disproportionation**:
- Disproportionation occurs when a single element in a compound is both oxidized (loses electrons) and reduced (gains electrons) in the same reaction.

2. **Analyze the Given Examples**:
- We need to evaluate each example to see if the same element is undergoing both oxidation and reduction.

3. **Example A**:
- **Oxidation States**:
- Mn is +4 (reactant) and +2 (product) → Mn is reduced.
- Cl is -1 (reactant) and 0 (product) → Cl is oxidized.
- **Conclusion**: Different elements are involved (Mn and Cl), so this does not represent disproportionation.

4. **Example B**:
- **Oxidation States**:
- O is -1 (reactant) and -2 (product) → O is reduced.
- O is -1 (reactant) and 0 (product) → O is oxidized.
- **Conclusion**: The same element (O) is both oxidized and reduced, indicating this is a disproportionation reaction.

5. **Example C**:
- **Oxidation States**:
- Cl is +5 (reactant) and +7 (product) → Cl is oxidized.
- Cl is +5 (reactant) and -1 (product) → Cl is reduced.
- **Conclusion**: The same element (Cl) is both oxidized and reduced, indicating this is also a disproportionation reaction.

6. **Final Conclusion**:
- Among the examples analyzed, **Example A** does not represent a disproportionation reaction because it involves different elements (Mn and Cl) undergoing oxidation and reduction, while Examples B and C do involve the same element undergoing both processes.

### Answer:
The correct option is **Example A**.

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