Which of the following is`//`are disproportionation redox changes?

Options

A. `(NH_(4))_(2)Cr_(2)O_(7)rarrN_(2)+Cr_(2)O_(3)+4H_(2)O`
B. `5H_(2)O_(2)+2CIO_(2)+2overset(ө)OHrarr2Cl^(ө)+5O_(2)+6H_(2)O`
C. `3ClO^(ө)rarrClO_(3)^(ө)+Cl^(ө)`
D. `2HCuCl_(2)overset("Dilution")underset("with water")rarrCu+Cu^(2+)+4Cl^(ө)+2H^(o+)`

Explanation

To determine which of the given reactions are disproportionation redox changes, we need to analyze each reaction to see if any element undergoes both oxidation and reduction simultaneously. Disproportionation reactions involve a single species being oxidized and reduced at the same time.

### Step-by-Step Solution:

1. **Identify the Reactions**:
- We have four reactions to analyze. Let's denote them as Reaction 1, Reaction 2, Reaction 3, and Reaction 4.

2. **Analyze Reaction 1**:
- This reaction is a decomposition reaction.
- **Oxidation States**: There is no change in oxidation states of any elements involved.
- **Conclusion**: No oxidation or reduction occurs. Therefore, this is **not a disproportionation reaction**.

3. **Analyze Reaction 2**:
- In this reaction, we need to check the oxidation states of the elements involved.
- **Oxidation States**: The oxidation states do not change for any element in a way that indicates simultaneous oxidation and reduction.
- **Conclusion**: This is a redox reaction, but it is **not a disproportionation reaction**.

4. **Analyze Reaction 3**:
- Here, we have chlorine in different oxidation states.
- **Oxidation States**: Chlorine changes from +2 to +5 (oxidation) and from +2 to -1 (reduction).
- **Conclusion**: Chlorine undergoes both oxidation and reduction. This is a **disproportionation reaction**.

5. **Analyze Reaction 4**:
- In this reaction, we also have copper in different oxidation states.
- **Oxidation States**: Copper changes from +1 to 0 (reduction) and from +1 to +2 (oxidation).
- **Conclusion**: Copper undergoes both oxidation and reduction. This is also a **disproportionation reaction**.

6. **Final Conclusion**:
- Out of the four reactions, **Reactions 3 and 4 are disproportionation redox reactions**, while Reactions 1 and 2 are not.

### Summary:
- **Disproportionation Reactions**: Reaction 3 and Reaction 4.
- **Not Disproportionation Reactions**: Reaction 1 and Reaction 2.