Which functional group is represented by R-CHO?

The structure R-CHO represents an aldehyde because it contains a carbonyl group (C=O) bonded to a hydrogen atom. In this representation, "R" stands for a hydrocarbon chain or group, which can vary in complexity, while "CHO" indicates that there is a carbon atom double-bonded to an oxygen atom (the carbonyl) and single-bonded to a hydrogen atom. This arrangement is characteristic of aldehydes, which are defined by having the carbonyl group at the terminal position of the carbon chain.

Aldehydes are notable for their reactivity and are often involved in various organic reactions due to the polar nature of the carbonyl group. The presence of the hydrogen atom attached directly to the carbonyl carbon is a defining feature of aldehydes, distinguishing them from other functional groups.

In contrast, alcohols contain a hydroxyl group (-OH), ketones have a carbonyl group that is flanked by carbon atoms on both sides (not at the end), and carboxylic acids consist of a carbonyl group and a hydroxyl group together (-COOH). Each of these functional groups has distinct structural features that differentiate them from aldehydes, which is why the correct identification