Which of the following is a disproportionation reaction?

Options

A. `Cl_2(g) + 2OH^(-) (aq) to ClO^(-)(aq) + Cl^(-)(aq) + H_2O(l)`
B. `Cl_(2)(g) + 2I^(-)(aq) to 2Cl^(-)(aq) + I_(2)(s)`
C. `2Fe(s) + 3H_(2)O(l) overset(Delta)rarr Fe_(2)O_(3)(s) + 3H_(2)(g)`
D. `2H_(2)O(l) + 2F_(2)(g) rarr 4HF(aq) + O_(2)(g)`

Answer

To determine which of the following reactions is a disproportionation reaction, we first need to understand what a disproportionation reaction is. A disproportionation reaction is a specific type of redox reaction in which a single substance is both oxidized and reduced, resulting in two different products with different oxidation states of the same element.

### Step-by-Step Solution:

1. **Identify the Reactions**: We need to look at the given reactions and identify the oxidation states of the elements involved in each reaction.

2. **Determine Oxidation States**: For each reaction, calculate the oxidation states of the relevant elements before and after the reaction.

3. **Check for Simultaneous Change**: Look for a single element that undergoes both oxidation (increase in oxidation state) and reduction (decrease in oxidation state) in the same reaction.

4. **Analyze Each Reaction**:
- **Example 1**: 2H₂O₂ → 2H₂O + O₂
- Here, the oxidation state of oxygen changes from -1 in H₂O₂ to -2 in H₂O (reduction) and to 0 in O₂ (oxidation). This is a disproportionation reaction.

- **Example 2**: Cl₂ + 2I⁻ → 2Cl⁻ + I₂
- Chlorine (Cl) goes from 0 to -1 (reduction) and iodine (I) goes from -1 to 0 (oxidation). This is not a disproportionation reaction since different elements are involved.

- **Example 3**: 2Fe²⁺ → 2Fe³⁺ + 2e⁻
- Here, iron (Fe) is only oxidized from +2 to +3. There is no reduction occurring for the same element, so this is not a disproportionation reaction.

- **Example 4**: H₂ + F₂ → 2HF
- In this reaction, hydrogen (H) remains at +1 and fluorine (F) goes from 0 to -1. Again, there is no simultaneous oxidation and reduction of the same element.

5. **Conclusion**: The only reaction that fits the definition of a disproportionation reaction is the first example: 2H₂O₂ → 2H₂O + O₂.

### Final Answer:
The disproportionation reaction is **2H₂O₂ → 2H₂O + O₂**.