How many of the following are more acidic than phenol

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answer is 4.

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Detailed Solution

Compound-wise check:

Thiol (–SH group) → Thiols are more acidic than alcohols/phenols because the S–H bond is weaker and the conjugate base (RS⁻) is more stable. ✅ More acidic
o-Chlorophenol → The –Cl group is electron-withdrawing (–I effect) which stabilizes the phenoxide ion. More acidic
p-Chlorophenol → Same reason (–Cl is electron-withdrawing), so more acidic than phenol.
p-Nitrophenol → –NO₂ is a strong –M and –I group, greatly stabilizes conjugate base. Very acidic.
p-Methoxyphenol → –OCH₃ is an electron-donating group (+M effect), which destabilizes the conjugate base. Less acidic
p-Cyanophenol → –CN is electron-withdrawing, stabilizes conjugate base.
o-Nitrophenol → Strong –NO₂ group, plus intramolecular H-bonding helps release proton easily.
Chlorocyclohexanol → Not aromatic, OH on cyclohexane. Lacks resonance stabilization like phenol. Less acidic
Carbonic acid (H₂CO₃) → pKa ≈ 6.3, much stronger acid than phenol.

Counting the more acidic ones:

1 (thiol), 2, 3, 4, 6, 7, 9
Total = 6 compounds

Final Answer: 6 compounds are more acidic than phenol.

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