The acetate anion has two resonance structures of the same energy; one in which the π bond is on one oxygen, the other where it's on the other oxygen.
2
3 structures
2
3 =]
For SO3, two equivalent resonance structures are sufficient to describe the bonding.
The sulfate ion has four resonance structures.
2
there are 2
3 structures
2
3
4
3 =]
there are three resonating structures of H2CO3 OH+-------C------O+-------oh+
There are 2 resonance structures for ozone.
In chemistry, resonance is a way of describing bonding in certain molecules or ions by the combination of several contributing structures (or forms, also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory
three