Final answer:
In the gaseous state, monatomic gases like helium (He), neon (Ne), and the noble gases exist as single atoms and are considered molecules. Diatomic gases like hydrogen (H₂), nitrogen (N₂), and oxygen (O₂) consist of two atoms that are covalently bonded together and are also referred to as molecules.
Step-by-step explanation:
When a substance is in the gaseous state, the atoms or molecules are not typically bonded together. In the case of monatomic gases like helium (He), neon (Ne), and the noble gases, each atom exists as a single entity and is considered a molecule in this context.
On the other hand, diatomic gases like hydrogen (H₂), nitrogen (N₂), and oxygen (O₂) consist of two atoms that are covalently bonded together and are also referred to as molecules.