Organic Chemistry MCAT Practice Exam 2026 - Free MCAT Practice Questions and Study Guide

A ketone is a type of organic compound characterized by the presence of a carbonyl group (C=O) bonded to two carbon atoms. This functional group is typically found in a structure where the carbonyl carbon is situated between two other carbon atoms.

Acetone, as the correct response, is a prime example of a ketone. Specifically, acetone, or propan-2-one, has the structure where the carbonyl carbon is flanked by two methyl groups. This fulfills the ketone criterion, as it indeed contains a carbonyl group that is bonded to two other carbon atoms.

In contrast, butanal is an aldehyde, defined by having a carbonyl carbon bonded to at least one hydrogen atom and typically found at the end of a carbon chain. Formic acid is a carboxylic acid that contains a carbonyl group bonded to a hydroxyl group and involves different reactivity and properties. Lastly, hexanol is an alcohol, featuring a hydroxyl (-OH) group instead of a carbonyl, which further distinguishes it from ketones.

Understanding the structural requirements for ketones alongside differentiating them from other functional groups is key in organic chemistry.