II. Read the passage given below and answer the following questions :
The reaction of phenol with aqueous sodium hydroxide indicates that phenols are stronger acids than alcohols and water. Due to the higher electronegativity of `sp^(2)` hybridised carbon of phenol to which -OH is attached, electron density decreases on oxygen. This increases the polarity of O-H bons and results in an increase in ionisation of phenols than that of alcohols. Now let us examine the stabilities of alkoxide and phenoxide ions In alkoxide ion, the phenoxide ion, the charge is delocalised. The delocalisation of negative charge makes phenoxide ion more stable and favours the ionisation of phenol.
Which of the following is most acidic ?

Options

A. Benzyl alcohol
B. Cyclohexanol
C. Phenol
D. m-Chlorophenol

Explanation

To determine which compound is the most acidic among benzyl alcohol, cyclohexanol, phenol, and meta-chlorophenol, we can analyze the acidity based on the stability of their conjugate bases.

### Step-by-Step Solution:

1. **Understanding Acidity**:
- Acidity is determined by the ability of a compound to donate a proton (H⁺). The more stable the conjugate base, the stronger the acid.

2. **Identifying the Compounds**:
- We have four compounds to consider:
- Benzyl alcohol (C₆H₅CH₂OH)
- Cyclohexanol (C₆H₁₁OH)
- Phenol (C₆H₅OH)
- Meta-chlorophenol (C₆H₄Cl(OH))

3. **Analyzing the Conjugate Bases**:
- **Benzyl alcohol** forms the benzyl alkoxide ion (C₆H₅CH₂O⁻).
- **Cyclohexanol** forms the cyclohexyl alkoxide ion (C₆H₁₁O⁻).
- **Phenol** forms the phenoxide ion (C₆H₅O⁻), which is stabilized by resonance.
- **Meta-chlorophenol** forms the meta-chlorophenoxide ion (C₆H₄ClO⁻), which is also stabilized by resonance and the -I effect of the chlorine atom.

4. **Comparing Stability of Conjugate Bases**:
- The phenoxide ion (C₆H₅O⁻) is stabilized by resonance, allowing the negative charge to be delocalized over the aromatic ring.
- The meta-chlorophenoxide ion (C₆H₄ClO⁻) benefits from the electron-withdrawing -I effect of the chlorine atom, which further stabilizes the negative charge through resonance.
- The alkoxide ions (benzyl and cyclohexyl) do not have this resonance stabilization, making them less stable compared to the phenoxide ions.

5. **Conclusion**:
- Since the phenoxide ion is more stable than the alkoxide ions and the meta-chlorophenoxide ion is even more stabilized due to the presence of the chlorine atom, we conclude that:
- **Meta-chlorophenol** is the most acidic among the given compounds.

### Final Answer:
**Meta-chlorophenol is the most acidic compound.**