The sulfate ion SO4^-2 has four resonance structures. In each resonance structure, the sulfur atom is at the center, and the four oxygen atoms are bonded to it. The sulfur atom has a formal charge of +2, and two of the oxygen atoms have a formal charge of -1, while the other two oxygen atoms have a formal charge of 0. The negative charges are distributed among the oxygen atoms.Here are the four resonance structures:1. O=S -O^- -O^- O2. O -O^- S=O -O^- 3. -O^- O=S -O^- O4. O -O^- S -O^- =OIn each resonance structure, there are two double bonds and two single bonds between the sulfur and oxygen atoms. The double bonds have a bond order of 2, while the single bonds have a bond order of 1.The resonance structures contribute to the overall stability of the sulfate ion by delocalizing the negative charge over the four oxygen atoms. This delocalization of charge reduces the electrostatic repulsion between the negatively charged oxygen atoms and stabilizes the molecule.In reality, the sulfate ion does not have distinct double and single bonds. Instead, the four sulfur-oxygen bonds are equivalent, with a bond order of 1.5. This is because the electrons in the double bonds are shared equally among all four oxygen atoms, resulting in an average bond order between a single bond and a double bond. This equal sharing of electrons further contributes to the stability of the sulfate ion.