Answer: Phenol.
- A Methanol
- B Phenol
- C Ether
- D Ethanol
Correct answer: B. Phenol
Explanation: Phenol reacts with neutral ferric chloride to give a violet colour.
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.