Q43 - Functional groups

The correct answer is C) Ketones.

Read the name: pent- means 5 carbons and the suffix -one means a ketone, a C=O group bonded to two carbons. Examples: pentan-2-one (CH₃COCH₂CH₂CH₃) and pentan-3-one (CH₃CH₂COCH₂CH₃).

A) Incorrect: Carboxylic acids end in “-oic acid” (pentanoic acid) and contain –COOH.

B) Incorrect: Lactones are cyclic esters.

C) Correct: The suffix “-one” denotes a ketone.

D) Incorrect: Alcohols end in “-ol” (pentanol).

E) Incorrect: A hydroxyketone would have both –OH and C=O, and its name would include “hydroxy” (such as hydroxypentanone).