Determine the chemical formulas for the following compounds:
A) a covalent compound whose molecules contain 2 carbon atoms, 6 hydrogen atoms and an oxygen atom
B) a compound composed of Na+ and O2- ions
C) a compound composed of Sn4+ and S2- ions
D) a compound composed of Fe2+ and PO4 3- ions
Solution provides chemical formulae for the identified compounds and explains how these are determined.