The hydrogen sulfate or bisulfate ion HSO4– can act as either an acid or a base in water solution. In which of the following equations does HSO4– act as an acid? HSO4– + OH– → H2SO4 + O2– HSO4– + H3O+ → SO3 + 2H2O HSO4– + H2O → SO42– + H3O+ HSO4– + H2O → H2SO4 + OH– None of these choices are correct.