What type of functional group is present in both formaldehyde and acetaldehyde?

The correct answer is based on the presence of a specific functional group known as the aldehyde group, which is characterized by the structure CHO. Both formaldehyde and acetaldehyde contain this functional group.

Formaldehyde (HCHO) consists of one carbon atom double-bonded to an oxygen atom and single-bonded to a hydrogen atom. Acetaldehyde (CH3CHO) features a carbon atom that is also double-bonded to an oxygen and single-bonded to a methyl group (CH3) and a hydrogen atom. The defining aspect of aldehydes is that they have at least one hydrogen atom attached to the carbonyl (C=O) carbon, distinguishing them from other functional groups such as ketones, which do not have this hydrogen.

Understanding the aldehyde functional group helps in recognizing the structural and chemical similarities between compounds like formaldehyde and acetaldehyde, as both exhibit the characteristic reactivity and properties associated with aldehydes.