Question

Arrange the following in decreasing order of their boiling points:

• A. a>b>d>c
• B. a>c>d>b
• C. b>c>d>a
• D. c>a>b>d

Hint:

Hydrogen bonding significantly increases boiling point. Alcohol>Amine>Amide>Tertiary Amine.

Answer 1

The Correct Option is A

Boiling point order depends on hydrogen bonding and molecular interactions:
- (a) Alcohol (OH): Strong H-bonding → highest BP
- (b) Primary amine (NH\(_2\)): Less polar than OH, but can H-bond → moderate BP
- (d) Amide (CONH\(_2\)): Strong intermolecular H-bonding, but resonance lowers availability
- (c) Tertiary amine (N(CH\(_3\))\(_2\)): No H-bonding → lowest BP
\[ \text{BP order: } \text{Alcohol}>\text{Amine}>\text{Amide}>\text{Tertiary amine} \Rightarrow a>b>d>c \]