What is the formula for sulfate?

The formula for sulfate is represented as SO4^2-. Sulfate is a polyatomic ion composed of one sulfur atom bonded to four oxygen atoms, carrying an overall charge of -2. This formula reflects the oxidation state of sulfur, which is +6 in this case, as each oxygen typically has an oxidation state of -2. The tetrahedral arrangement of the four oxygen atoms around the sulfur atom helps to explain the stability and common occurrence of the sulfate ion in various chemical compounds and biological systems. With its -2 charge, sulfate is often found in salts and minerals, as well as in biological molecules such as amino acids and proteins.

The other choices represent different species: SO3^2- is the sulfite ion, which has only three oxygen atoms and a -2 charge; HSO3- is the bisulfite or hydrogen sulfite ion, which is the protonated form of sulfite; while HSO4- represents the bisulfate ion, which is derived from sulfate by adding a hydrogen ion, creating a -1 charge. None of these choices correctly represent the sulfate ion itself, as only SO4^2- has the correct number of oxygen atoms and charge.