Assertion: Carboxylic acids have higher boiling points than alkanes.

 Reason:  Carboxylic acids are resonance hybrids.

Both Assertion and Reason are correct and the Reason is not the correct explanation for the Assertion.

The correct answer is option 2. Both Assertion and Reason are correct and the Reason is not the correct explanation for the Assertion.

Let us examine the assertion and the reason separately and then analyze why the reason does not explain the assertion.

Assertion: Carboxylic acids have higher boiling points than alkanes.

This statement is correct. Carboxylic acids indeed have higher boiling points compared to alkanes of similar molecular weight. The primary reason for this is the ability of carboxylic acids to form hydrogen bonds. Carboxylic acids can dimerize through hydrogen bonding, where two molecules of carboxylic acid form a dimer, leading to significant intermolecular attractions that require more energy (higher temperature) to break. This results in higher boiling points.

Reason: Carboxylic acids are resonance hybrids.

This statement is also correct. Carboxylic acids exhibit resonance, meaning the electron distribution within the carboxyl group \((-COOH)\) can be delocalized between the oxygen atoms. This resonance stabilization contributes to the overall stability of the molecule.

The reason provided (carboxylic acids are resonance hybrids) is not the correct explanation for the assertion (carboxylic acids have higher boiling points than alkanes). While resonance stabilization is an important chemical property of carboxylic acids, it does not directly affect their boiling points.

Correct Explanation:

The higher boiling points of carboxylic acids are primarily due to the formation of strong hydrogen bonds between the carboxyl groups of neighboring molecules. Hydrogen bonding is a type of strong dipole-dipole interaction that significantly increases the energy required to separate molecules in the liquid phase, thus raising the boiling point.

In contrast, alkanes are nonpolar molecules and exhibit only weak van der Waals (dispersion) forces between their molecules. These forces are much weaker than hydrogen bonds, leading to much lower boiling points for alkanes compared to carboxylic acids of similar molecular weight.

Conclusion: Both the assertion and the reason are correct as individual statements, but the reason does not explain why carboxylic acids have higher boiling points. Therefore, the correct answer is: Both Assertion and Reason are correct and the Reason is not the correct explanation for the Assertion.