Which ion is represented by the formula SO3(2-)?

The ion represented by the formula SO3(2-) is sulfite. This is because the "SO" indicates that it contains sulfur (S) and oxygen (O) atoms, and the (2-) indicates that this ion has a charge of negative two. The sulfite ion specifically consists of one sulfur atom bonded to three oxygen atoms and carries a -2 charge, which fits the given formula perfectly.

Sulfate, which is indicated by the formula SO4(2-), contains one sulfur atom and four oxygen atoms and also carries a -2 charge, but it is distinct from sulfite due to the one additional oxygen atom. Thiosulfate, represented by the formula S2O3(2-), contains a different structure entirely, incorporating two sulfur atoms. Nitrate, on the other hand, is represented by the formula NO3(-), indicating it is composed of nitrogen and oxygen, bearing a different count and configuration of atoms than what is found in sulfite. Therefore, the identification of SO3(2-) as sulfite aligns correctly with its chemical composition and charge.