Which of the following is comproportionation reaction :

Options

A. `Cl_(2(g))+OH_((aq))^(-) to ClO_(3(aq))^(-) +Cl_((aq))^(-) +H_(2)O_((l))`
B. `Ag_((aq))^(2+)+Ag_((s)) to 2Ag_((aq))^(+)`
C. `Na_((s))+H_(2)O_((i)) to NaOH_((aq))+H_(2(g))`
D. `Zn_((s))+CuSO_(4(aq)) to ZnSO_(4(aq))+Cu_((s))`

Answer

To determine which of the given reactions is a comproportionation reaction, we first need to understand the definition and characteristics of such reactions.

### Step-by-Step Solution:

1. **Understand Comproportionation Reaction**:
- A comproportionation reaction occurs when two reactants containing the same element in different oxidation states react to form a product where the oxidation state of that element is the same.

2. **Identify the Options**:
- We will analyze the provided options (A, B, C, D) to find the one that fits the definition of a comproportionation reaction.

3. **Analyze Each Option**:
- **Option A**: Check if it has the same element in different oxidation states.
- **Option B**: Check if it has the same element in different oxidation states.
- **Option C**: Check if it has the same element in different oxidation states.
- **Option D**: Check if it has the same element in different oxidation states.

4. **Examine Option B**:
- In option B, if we have Ag in +2 and 0 oxidation states, and they combine to form Ag with a +1 oxidation state, this satisfies the criteria for a comproportionation reaction:
- Reactants: Ag(+2) and Ag(0)
- Product: Ag(+1)
- Here, Ag(+2) is reduced to Ag(+1) and Ag(0) is oxidized to Ag(+1).

5. **Conclusion**:
- Based on the analysis, Option B is the correct answer as it demonstrates a comproportionation reaction.

### Final Answer:
**Option B is a comproportionation reaction.**