The following reagent converts `C_(6) H_(5) COCHO to C_(6) H_(5) CHOHCOONa`

Options

A. Aq. NaOH
B. Acidic `Na_(2)S_(2)O_(3)`
C. `Na_(2)CrO_(4)//H_(2)SO_(4)`
D. `NaNO_(2)//HCl`

Answer

To solve the question, we need to identify the reagent that converts benzaldehyde (C6H5CHO) to sodium benzoate (C6H5COONa). The reaction involves the addition of a reagent that facilitates this transformation.

### Step-by-Step Solution:

1. **Identify the Reactant**: The starting compound is benzaldehyde, which has the formula C6H5CHO.

2. **Identify the Product**: The desired product is sodium benzoate, which has the formula C6H5COONa.

3. **Determine the Reaction Type**: The conversion of benzaldehyde to sodium benzoate suggests a reaction involving the formation of a carboxylic acid followed by neutralization with sodium hydroxide (NaOH).

4. **Identify the Reagent**: The reagent that can convert benzaldehyde to a carboxylic acid is typically an oxidizing agent. However, in this case, we are looking for a reagent that can facilitate the addition of a hydroxyl group (OH) to the carbonyl carbon of benzaldehyde.

5. **Use of Sodium Hydroxide (NaOH)**: Aqueous sodium hydroxide (NaOH) can react with benzaldehyde in a reaction known as the aldol condensation or a similar reaction, leading to the formation of the corresponding sodium salt of the carboxylic acid.

6. **Mechanism of Reaction**:
- The hydroxide ion (OH-) from NaOH attacks the carbonyl carbon of benzaldehyde.
- This results in the formation of a tetrahedral intermediate.
- Subsequently, a rearrangement occurs, and water is eliminated, leading to the formation of the sodium salt of benzoic acid (C6H5COONa).

7. **Final Product**: The final product after the reaction is C6H5COONa, which is sodium benzoate.

### Conclusion:
The reagent that converts C6H5CHO to C6H5COONa is **aqueous sodium hydroxide (NaOH)**.