Which of the following reagents cannot be used to distinguish between phenol and benzyl alcohol ?

Options

A. `Br_(2)//C Cl_(4)`
B. NaOH
C. `NAHCO_(3)`
D. `FeCl_(3)` (neutral)

Explanation

To determine which reagent cannot be used to distinguish between phenol and benzyl alcohol, we need to analyze the structures and chemical properties of both compounds and the reagents listed.

### Step-by-Step Solution:

1. **Identify the Structures**:
- **Phenol**: It has a hydroxyl group (-OH) directly attached to a benzene ring.
- **Benzyl Alcohol**: It has a hydroxyl group (-OH) attached to a benzyl group (C6H5-CH2-).

2. **Analyze the Reagents**:
- **Br2/CCl4**: This reagent can react with phenol to form a dibrominated product. However, due to steric hindrance, benzyl alcohol will not react in the same way. Thus, this reagent can distinguish between the two.
- **NaOH**: This reagent reacts with phenols to form sodium phenoxide but does not react with benzyl alcohol. Therefore, NaOH can also distinguish between phenol and benzyl alcohol.
- **NaHCO3**: This reagent does not react with either phenol or benzyl alcohol significantly. Thus, it cannot distinguish between the two.
- **FeCl3**: This reagent will react with phenol to form a colored complex, indicating the presence of phenol. It does not react with benzyl alcohol. Therefore, it can distinguish between the two.

3. **Conclusion**:
- Among the reagents analyzed, **NaHCO3** is the one that cannot be used to distinguish between phenol and benzyl alcohol because it does not react with either compound.

### Final Answer:
The reagent that cannot be used to distinguish between phenol and benzyl alcohol is **NaHCO3**.