Answer: -OH.
- A -CHO
- B -OH
- C -COOH
- D -NH<sub>2</sub>
Correct answer: B. -OH
Explanation: Alcohols contain the hydroxyl functional group represented by -OH.
The phenoxide ion's negative charge spreads into the aromatic ring through resonance, lowering its energy and making phenol give up its proton more easily; an alkoxide ion (from a plain alcohol) has nowhere to delocalise the charge, making alcohols far less acidic.
Concept context
Oxygen-containing organic compounds. Understand the acidic nature of phenols, reactions of alcohols (dehydration, oxidation, esterification), and properties of ethers. Includes industrial applications and named reactions.