1. Bisulfate or Hydrogen sulfate   HSO4   S   HSO3   O   Hint Half-n-half Clue   2. Nitrate   NH4   HSO4   S   NO3   Half-n-half Clue   3. Bicarbonate or Hydrogen carbonate   S   PO4   HCO3   NH4   Half-n-half Clue   4. Bisulfite or Hydrogen sulfite   S   O   HSO3   SO4   Half-n-half Clue   5. Iodide   SO4   I   S   Br   Half-n-half Clue   6. Oxide   HSO3   OH   NO3   O   Half-n-half Clue   7. Sulfite   Br   OH   HCO3   SO3   Half-n-half Clue