1. Sulfate   SO4   HSO4   S   I   Hint Half-n-half Clue   2. Ammonium   CO3   Cl   PO4   NH4   Half-n-half Clue   3. Hydroxide   OH   Br   PO4   HSO4   Half-n-half Clue   4. Carbonate   S   CO3   Cl   SO4   Half-n-half Clue   5. Sulfite   SO3   Cl   S   NO3   Half-n-half Clue   6. Bisulfite or Hydrogen sulfite   HSO3   HCO3   Br   SO3   Half-n-half Clue   7. Nitrate   NO3   Cl   SO3   O   Half-n-half Clue