There are three possible resonance structures for the carbonate ion CO3^-2 . Here are the structures:1. O=C-O - -O - | O2. O - -C=O | O - 3. O - -O - | C=OIn each structure, the carbon atom is bonded to one oxygen atom with a double bond and the other two oxygen atoms with single bonds. The negative charges are distributed among the oxygen atoms. These three resonance structures contribute equally to the overall structure of the carbonate ion, which is a resonance hybrid of these three forms.