1. Bisulfite or Hydrogen sulfite   HCO3   SO4   HSO3   HSO4   Hint Half-n-half Clue   2. Iodide   CO3   OH   S   I   Half-n-half Clue   3. Bisulfate or Hydrogen sulfate   O   SO3   HSO4   HSO3   Half-n-half Clue   4. Carbonate   OH   HSO3   CO3   NH4   Half-n-half Clue   5. Phosphate   NH4   O   PO4   SO4   Half-n-half Clue   6. Ammonium   NO3   HSO3   NH4   HSO4   Half-n-half Clue   7. Nitrate   CO3   OH   NO3   SO3   Half-n-half Clue