State which of the following reactions is neither oxidation nor reduction -

Options

A. `Na rarr NaOH`
B. `Cl_(2) rarr Cl^(-) + ClO_(3) ^(-)`
C. `P_(2) O_(5) rarr H_(4) P_(2) O_(7)`
D. `Zn+H_(2) SO_(4) rarr ZnSO_(4) +H_(2)`

Explanation

To determine which of the given reactions is neither an oxidation nor a reduction, we will analyze the oxidation states of the elements involved in each reaction.

### Step-by-Step Solution:

1. **Understand Oxidation and Reduction**:
- **Oxidation** is defined as the loss of electrons or an increase in oxidation state.
- **Reduction** is defined as the gain of electrons or a decrease in oxidation state.

2. **Identify the Reactions**:
- We will analyze each reaction provided in the question to check for changes in oxidation states.

3. **Analyze Each Reaction**:
- **Reaction 1**: Sodium (Na) changes from 0 (elemental form) to +1. This indicates an increase in oxidation state (oxidation).
- **Reaction 2**: Chlorine (Cl2) changes from 0 (elemental form) to -1. This indicates a decrease in oxidation state (reduction).
- **Reaction 3**: Phosphorus in P2O5 has an oxidation state of +5. In H4P2O7, phosphorus also has an oxidation state of +5. Since there is no change in oxidation state, this reaction does not involve oxidation or reduction.
- **Reaction 4**: Zinc (Zn) goes from 0 to +2 (oxidation), while hydrogen (H) goes from +1 to 0 (reduction). This is a redox reaction.

4. **Conclusion**:
- The only reaction where there is no change in oxidation states is **Reaction 3** (P2O5 to H4P2O7). Therefore, this reaction is neither oxidation nor reduction.

### Final Answer:
The reaction that is neither oxidation nor reduction is **Reaction 3** (P2O5 to H4P2O7).

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