Which of the following are elements, which are mol-
ecules but not compounds, which are compounds but
not molecules, and which are both compounds and
molecules? (a) SO₂, (b) Sg, (c) Cs, (d) N₂O5, (e) 0.
(f) O₂, (g) 03. (h) CH₁, (i) KBr, (j) S. (k) P4, (1) LiF