What distinguishes aldehydes from ketones?

Aldehydes are distinguished from ketones primarily by the position of the carbonyl group (C=O) within the molecule. In aldehydes, the carbonyl group is located at the end of the carbon chain, meaning that it is bonded to a terminal carbon atom. This placement allows aldehydes to be characterized by the general formula RCHO, where R can be a hydrogen atom or a hydrocarbon group.

In contrast, ketones feature the carbonyl group situated within the carbon chain, specifically between two carbon atoms. They follow the general formula RC(=O)R', where R and R' can be alkyl groups or other carbon-containing groups. This fundamental difference in carbonyl position is what differentiates aldehydes from ketones.

The other options do not accurately reflect distinguishing features between aldehydes and ketones. For example, aldehydes are not always aromatic, as many are aliphatic compounds as well. Furthermore, having a chiral center is not a requirement for ketones despite some ketones being chiral; it is not a defining characteristic of that functional group. Lastly, aldehydes are indeed capable of undergoing oxidation reactions, which is one of their notable chemical behaviors.