Which compound will exhibit the lowest boiling point?

N,N-dimethylethanamine

The correct answer is Option (4) → N,N-dimethylethanamine

Reason (Boiling Point Order):

All compounds have similar molecular weight (~73 g/mol), so intermolecular forces decide the boiling point.

• Alcohols have strongest H-bonding → highest B.P.
• Primary amines → can form H-bonds → moderate B.P.
• Secondary amines → weaker H-bonding → lower B.P.
• Tertiary amines → no H-bonding → only van der Waals → lowest boiling point

Final Answer: N,N-Dimethylethanamine (also known as trimethylethanamine or simply trimethylamine) has the lowest boiling point.