Answer: Azo dye.
- A Azo dye
- B Phenol
- C Amine
- D Haloarene
Correct answer: A. Azo dye
Explanation: Azo coupling forms a highly coloured azo compound (-N=N-) used in dyes.
In aniline, the nitrogen's lone pair is pulled into the benzene ring through resonance, leaving less electron density available to accept a proton - which is why aniline is a much weaker base than methylamine, where the lone pair is fully available.
Concept context
Nitrogen-containing organic compounds. Covers classification (primary, secondary, tertiary), basicity comparison, preparation methods, and reactions including diazotization and coupling, key for understanding dyes and pharmaceuticals.