Acetone is a three-carbon aldehyde. True/False.

The answer is False but I can't comprehend WHY. It's a ketone and a ketone is an aldehyde. It has only 3 C atoms. Why is it false here?

Answer: acetone is a ketone and not an aldehyde. Therefore it's false

Explanation:

Acetone is of structure CH3-CO-CH3

which makes it a ketone.

Both aldehyde and ketone have a carbonyl group but there is difference between aldehyde and ketone.

Aldehydes have a general formula R-CHO

where R is a methyl group including H atom, and CHO is the functional group.

While

Ketone have the general formula R-CO-Ri

where R and Ri are methyl groups excluding H atom, and CO is the functional group.

Hint: ketones usually end with the suffix "one" as in acetone.