I personally think this problem is very bad. It is their fault. It is nonsense when they are asking us to classify elements and molecules. O2 and N2 could very technically still be elements, too, but they actually form molecules.
O2, N2, Br2, F2, etc. are known as molecules and more technically called diatomic molecules. o3, etc. are triatomic molecules.
Chemistry: A Molecular Approach 5th edition
Textbook by Nivaldo J. Tro
Molecular elements( eg. H, O, N, F, etc.) exist in nature as molecules. H2, N2, O2, F2,Cl2, Br2, I2, all are diatomic molecules. We call them all molecules. This is very basic and common knowledge for chemistry majors.
A molecule is an assemblage of one or more atoms, which may or may not be identical. Diatomic molecules are divided into homonuclear (identical atoms) and heteronuclear (different atoms) diatomic molecules.
Triatomic molecules are molecules composed of three atoms, of either the same or different chemical elements. Examples include H2O, CO2 (pictured), HCN, O3 (ozone) and NO2
3.05: Pure Substances and Mixtures
I submitted an appeal this issue yesterday.