Which step of the scientific method includes a prediction? A).Ask a question.
B).Construct a hypothesis.
C).Do background research.
D).Test with an experiment.

Ketone

Explanation:

As you are stating here, we have a carbonated chain of three carbons, and the first and last has 3 Hydrogens, then this means that we have CH₃ . The center carbon is a carbon double bonded to oxygen.

In general terms this belongs to the carbonyl group. However, this alone does not represent a functional group, but when it's in a chain with other radycals or chains, it becomes a functional group.

In this case, the molecule you are talking here is the following:

CH₃ - CO - CH₃

This molecule is known as the Acetone, and has the general form of:

R - CO - R'

Which belongs to a ketone as a functional group.