Answer: A lone pair of electrons.
- A A lone pair of electrons
- B Double bond
- C Positive charge
- D Electronegativity
Correct answer: A. A lone pair of electrons
Explanation: The lone pair on nitrogen enables amines to accept protons (Bronsted base) or donate to Lewis acids.
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.