Concept:Melting point (m.p) is determined by the ability of molecules to pack efficiently in a solid crystal lattice and the extent of intermolecular hydrogen bonding.
Solution:- Monocarboxylic acids possess only one carboxyl (\( -\text{COOH} \)) group, allowing for hydrogen bonding on only one end of the molecule.
- Dicarboxylic acids contain two \( -\text{COOH} \) groups (one at each end of the carbon chain).
- This allows them to form an extensive, continuous, cross-linked network of hydrogen bonds throughout the entire solid crystal lattice.
- Due to these drastically stronger intermolecular forces, dicarboxylic acids require vastly more energy to melt, giving them a much higher melting point.
Why other options are incorrect:It is not similar or random; the structural doubling of hydrogen-bonding sites guarantees a higher melting point for the dicarboxylic variant.
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