Final answer:
The correct answer is A) It is a weak base. The sulfate ion (SO42-) is the conjugate base of sulfuric acid, which is weak as it has a high pKb value.
Step-by-step explanation:
Sulfuric acid (H2SO4) is a diprotic acid that ionizes in water in two stages. The initial dissociation where it loses one hydrogen ion is nearly complete, producing the hydrogen sulfate ion (HSO4-), a strong conjugate base. This conjugate base can further lose a hydrogen ion to form the sulfate ion (SO42-), which is a weak base.
The hydrogen sulfate ion (HSO4-) can act as either an acid or a base depending on the other reactants in the solution, a property known as amphoteric. The dissociation of HSO4- to form sulfate ion (SO42-) is much less complete, reflecting its nature as a moderately strong acid. From the provided information, we deduce that the conjugate base of sulfuric acid is the sulfate ion, which being a weak base is associated with the answer A) It is a weak base. This is supported by the relationship pKa + pKb = pKw, where the pKa is 2.0 for H2SO4 and the pKb for SO42- is 12.01, indicating the weak basic nature of the conjugate base.