HPO4²⁻: This is the conjugate base of phosphoric acid. It has a charge of -2 and consists of one phosphorus atom bonded to four oxygen atoms, with one hydrogen atom removed.
H2PO4⁻: This is another conjugate base of phosphoric acid. It has a charge of -1 and consists of one phosphorus atom bonded to four oxygen atoms, with two hydrogen atoms removed.
H3PO4: This is phosphoric acid itself, which can donate three protons (H+) in water to form different ions such as H2PO4⁻ or HPO4²⁻.