See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Concept: Boiling points of amines depend on their ability to form intermolecular hydrogen bonds. Among isomeric amines (same molecular formula), the extent of hydrogen bonding decreases as the degree of substitution increases. Reasoning: - Primary (1°) amines have two N-H bonds, allowing extensive intermolecular hydrogen bonding. This raises the boiling point significantly. - Secondary (2°) amines have one N-H bond, allowing less intermolecular hydrogen bonding than primary amines, so their boiling points are lower than 1° amines. - Tertiary (3°) amines have NO N-H bonds at all. They cannot form intermolecular hydrogen bonds with each other (they can only act as hydrogen bond acceptors with water, not donors among themselves). Therefore, intermolecular forces are limited to van der Waals/dipole-dipole interactions only, resulting in the lowest boiling point among the three isomeric classes. Why other options fail: - (a) 1° amine: Has the most N-H bonds → highest boiling point among isomers, not the lowest. - (b) 2° amine: Has one N-H bond → intermediate boiling point, not the lowest. - (d) cannot predict: Incorrect because the trend is well-established based on hydrogen bonding capacity. Therefore, the correct answer is C.