Final answer:
The conjugate base of H₂SO₄ is the hydrogen sulfate ion (HSO₄⁻), which can act as both an acid and a base.
Step-by-step explanation:
The conjugate base of sulfuric acid (H₂SO₄) is the hydrogen sulfate ion (HSO₄⁻). When H₂SO₄ donates a proton (H⁺), it forms HSO₄⁻, which can still donate another proton, making it an amphiprotic species, meaning it can act as both an acid and a base. The strength of the conjugate base is related to the strength of the acid from which it is derived and their respective pKa and pKb values, hence the HSO₄⁻/SO₄²⁻ pair demonstrates this relationship. The sulfate ion (SO₄²⁻) is a weak base, thus HSO₄⁻ is a very weak base, consistent with being the conjugate base of the strong acid H₂SO₄.