Let's break down what that means:

* R: This represents a generic alkyl or aryl group. An alkyl group is a chain of carbon and hydrogen atoms, while an aryl group is a ring structure containing an aromatic ring.

* C: This is a carbon atom.

* H: This is a hydrogen atom.

* O: This is an oxygen atom.

Key Features of Aldehydes:

* Carbonyl Group (C=O): The carbon atom is double-bonded to an oxygen atom.

* Hydrogen Atom (H): The carbonyl carbon atom is also bonded to a hydrogen atom.

Examples of Aldehyde Formulas:

* Formaldehyde: HCHO

* Acetaldehyde: CH3CHO

* Benzaldehyde: C6H5CHO

Important Note:

The formula R-CO-R' represents a ketone, not an aldehyde. Ketones have a carbonyl group, but the carbon is bonded to two alkyl or aryl groups (R and R') instead of a hydrogen atom.