The 3rd group of anions consist of SO, PO and BO. They react neither with concentrated nor diluted HSO.
* Sulfates give a white precipitate of BaSO with BaCl which is insoluble in any acid or base.
* Phosphates give a yellow crystalline precipitate upon addition of HNO and ammonium molybdate and heating the solution.
* Borates give a green flame characteristic of ethyl borate when ignited with concentrated HSO and ethanol.