Answer is: H₂PO₄⁻ (dihydrogen phosphate).
Chemical reaction: HPO₄²⁻(aq) + H⁺(aq) ⇄ H₂PO₄⁻(aq).
According to Bronsted-Lowry
theory acid are donor of protons and bases are acceptors of protons (the
hydrogen cation or H⁺). Hydrogen phosphate is Bronsted base and it can accept proton and become conjugate acid.
