Final answer:
The chemical formula of the molecule represented by [ H_3C-CO-H ] is CH3CHO, which is known as acetaldehyde.
Step-by-step explanation:
The molecule given in the question is acetaldehyde, and its chemical formula is CH3CHO. It consists of a carbon chain with two carbon atoms. The first carbon atom is bonded to three hydrogen atoms (CH3), and the second carbon atom is double-bonded to an oxygen atom and single-bonded to a hydrogen atom (CHO), indicating the presence of an aldehyde functional group.
It is important while writing formulas to ensure each atom has the correct number of bonds that correspond to its valency.