Final answer:
The molecule with a resonance structure among the options given is CO32-, the carbonate anion, which has three equivalent resonance forms representing a resonance hybrid with equal bond lengths.
Step-by-step explanation:
The molecule among the given options that will have a resonance structure is CO32-, which is the carbonate anion. In the carbonate ion, the central carbon atom is bonded to three oxygen atoms. The carbonate ion cannot be represented by a single Lewis structure because one oxygen atom must have a double bond to satisfy the octet rule for the central carbon atom. However, all oxygen atoms are equivalent, which gives rise to three equivalent resonance forms. Therefore, the actual arrangement of electrons in the carbonate ion is a resonance hybrid, averaging the three structures and resulting in bonds of equal length and with a bond order of 1.33. This is consistent with experimental findings that all C-O bonds in the carbonate anion are identical.
The molecule that will have a resonance structure is the carbonate ion, CO3²-. It has three equivalent resonance forms, each with a different position for the carbon-oxygen double bond. The actual arrangement of electrons in the carbonate ion is the average of the three resonance structures. Experimentally, all three C-O bonds are found to be the same in length.