Question

Which of these substances are molecules?

Answer 1

A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. So I would say is all of them, as they all contain two atoms each even in the diatomics 

Answer 2

The answer is; All of them

A molecule is a stable chemical unit (with neutral charge) of atoms chemically bonded together (these bonds can be covalent, metallic, ionic, and etcetera). The molecule can, therefore, be of an element (contain atoms of the same element – in this case, N2 and O2) or a compound (atoms of different elements- in this case, H2O and NaCl).