Concept:Relative acidic strength is based on the resonance stabilization of the conjugate base anion.
Formula:$$ \text{RCOOH} > \text{Phenol} > \text{Water} > \text{Alcohols} $$
Solution:- Carboxylic acids form carboxylate ions where the negative charge is delocalized equally over two highly electronegative oxygen atoms. This makes them relatively strong weak acids.
- Phenol forms a phenoxide ion, delocalizing charge onto less electronegative carbon atoms in the ring. This makes it less acidic than carboxylic acids, but more acidic than water.
- Therefore, the true statement is that Phenol is less acidic than carboxylic acid.
Why other options are incorrect:A and B are false because phenol's resonance stabilization makes it about a million times more acidic than water. D is false because ethanol lacks resonance completely, making it far less acidic than phenol.
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