## Chemistry: Molecular Approach (4th Edition)

a) In the formula, we can see that there is 1 atom of Ca, 2 atoms of $N$ (1x2), and 4 atoms of $O$ (2x2). b) In the formula, we can see that there is 1 atom of Cu, 1 atom of $S$ and 4 atoms of $O$ c) In the formula, we can see that there is 1 atom of Al, 3 atoms of $N$ (1x3), and 9 atoms of $O$ (3x3) d) In the formula, we can see that there is 1 atom of Mg, 2 atoms of $C$ (1x2), 2 atoms of $H$ (1x2), and 6 atoms of $O$ (3x2)