2022 Aldehydes, Ketones and Carboxylic AcidsPhysical Properties of Aldehydes and Ketones Medium Question 20 of 91 in Aldehydes, Ketones and Carboxylic Acids

Given below are two statements: Statement I: The boiling points of aldehydes and ketones are higher than hydrocarbons of comparable molecular mass because of weak molecular association in aldehydes and ketones due to dipole-dipole interactions. Statement II: The boiling points of aldehydes and ketones are lower than the alcohols of similar molecular mass due to the absence of H-bonding. In the light of the above statements, choose the most appropriate answer from the options given below:

A Statement I is incorrect but Statement II is correct
B Both Statement I and Statement II are correct
C Both Statement I and Statement II are incorrect
D Statement I is correct but Statement II is incorrect

The answer is B.

Solution

Boiling point of compounds of comparable molecular mass: R–OH (H-bonding, strong association) > aldehydes/ketones (dipole-dipole interaction, weak association) > alkanes (non-polar) So both statements are correct.

Concept boiling points of carbonyl compounds

Aldehydes, Ketones and Carboxylic Acids in past papers

91 questions from this chapter have appeared across 27 exam years.