Concept:The acidic strength of phenol is governed by the stability of the phenoxide ion formed after a proton is lost. Stabilizing the negative charge increases acidity.
Formula:Not applicable to this conceptual question.
Solution:- The phenoxide ion carries a negative charge delocalized around the ring.
- If a substituent pulls electron density away from the ring (via -I inductive or -M mesomeric effects), it disperses and stabilizes the negative charge.
- Therefore, electron withdrawing substituents (like \(-\text{NO}_2\), halogens) stabilize the conjugate base and increase the acidic strength.
Why other options are incorrect:Electron donating substituents (like alkyl groups or -OH) push more electron density into the ring, concentrating the negative charge, destabilizing the ion, and severely decreasing acidity.
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