Question: what is the empirical formula for a compound which contains 80.3 zinc and the rest is oxygen?
Answer: Given the molar ratios, we divide thru by the lowest molar quantity to get an empirical formula of ZnO2 . The examiner has been nasty in that the expectation would have been ZnO . However, zinc does form a peroxo species composed of Zn2+ and O2−2 ions.