Explanation:
Na2O
This is an ionic compound because it contains a metal (Sodium) bonded to a non metal (Oxygen).
Copper
Atomic Element
Nitrogen
Atomic Element
Co3O4
This is an ionic compound because it contains a metal (Cobalt) bonded to a non metal (Oxygen).
N2O
This is a molecular compound because it contains a non metal (Nitrogen) bonded to a non metal (Oxygen).