The redox reaction among the following is

Options

A. `2NaOH+Cl_(2)rarr NaCl +NaOCl +H_(2)O`
B. Formation of ozone from atmospheric oxygen in the presence of sunlight
C. reaction of `[Co(H_(2)O)_(6)]Cl_(3)` with `AgNO_(3)`
D. reaction of `H_(2)SO_(4)` with `NaOH`

Answer

To determine which reaction is a redox reaction, we need to analyze the oxidation states of the elements involved in each reaction. A redox reaction involves the transfer of electrons, which results in changes in oxidation states.

### Step-by-Step Solution:

1. **Identify the Reactions**: We have several reactions to analyze. The first reaction is:
\[ 2 \text{NaOH} + \text{Cl}_2 \rightarrow \text{NaCl} + \text{NaOCl} + \text{H}_2\text{O} \]

2. **Assign Oxidation States**:
- In NaOH: Na is +1, O is -2, H is +1.
- In Cl2: Cl is 0 (elemental form).
- In NaCl: Na is +1, Cl is -1.
- In NaOCl: Na is +1, O is -2, Cl is +1.
- In H2O: H is +1, O is -2.

3. **Determine Changes in Oxidation States**:
- Chlorine (Cl) goes from 0 in Cl2 to -1 in NaCl (reduction).
- Chlorine (Cl) also goes from 0 in Cl2 to +1 in NaOCl (oxidation).

4. **Conclusion for the First Reaction**: Since there is both reduction (Cl from 0 to -1) and oxidation (Cl from 0 to +1), this reaction is a redox reaction.

5. **Analyze Other Reactions**:
- **Formation of Ozone**:
\[ 3 \text{O}_2 \rightarrow 2 \text{O}_3 \]
- Here, O is in the elemental form (0) and in ozone (O3) it remains in the same oxidation state. No redox reaction occurs.

- **Reaction of COH2O6Cl3 with AgNO3**:
- No change in oxidation states occurs in this reaction, indicating no redox reaction.

- **Neutralization Reaction**:
\[ \text{H}_2\text{SO}_4 + 2 \text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + 2 \text{H}_2\text{O} \]
- The oxidation states of all elements remain unchanged, indicating no redox reaction.

6. **Final Answer**: The only redox reaction among the options is the first one:
\[ 2 \text{NaOH} + \text{Cl}_2 \rightarrow \text{NaCl} + \text{NaOCl} + \text{H}_2\text{O} \]