# Which compound has resonance structures? [closed]

Which compound has resonance structures?

A. $$\ce{C6H12}$$
B. $$\ce{CH3CHO}$$
C. $$\ce{NaBr}$$
D. $$\ce{Na2CO3}$$

The answer key says D is correct, but I do not understand why $$\ce{Na2CO3},$$ which is an ionic compound between the polyatomic ion carbonate and sodium, can have resonance structures.

The other choices are equally confusing.

## closed as off-topic by Mithoron, user55119, Todd Minehardt, Jon Custer, TyberiusAug 14 at 14:52

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• Draw the structure of the carbonate ion, and you'll see. – Ivan Neretin Aug 13 at 5:26
• Arguably, A and B both have resonance structures, although those structures are not as good compared to what you could draw for D. – Zhe Aug 14 at 2:11
• @Zhe what are the resonance structures in A and B? I can only see possible hyper conjugation in B but nothing in A – StackUpPhysics Aug 14 at 13:06
• Technically speaking, you can just break a carbon-hydrogen or carbon-carbon bond and create an ion pair. You might do this to describe hyperconjugative stabilization of a cation or a 1,2-group shift. Like I said, it's not as good of a resonance structure as for D. Note that I didn't make this suggestion for C because that's almost purely an electrostatic interaction. But if you wanted to go nuts, draw a covalent bond between those two atoms. It is a resonance structure for the standard charge separated ion pair. – Zhe Aug 14 at 17:00
• @Zhe ok I get your point – StackUpPhysics Aug 15 at 5:52