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
For SO3, two equivalent resonance structures are sufficient to describe the bonding.
2
1
2
1
4
2
Two equivalent Lewis structures are necessary to describe the bonding in O3. These structures involve adding a double bond between each pair of oxygen atoms in alternate arrangements.
2
1
A single Lewis structure can be used to represent the bonding in SeF2O.
None. All the bonds are single bonds as is normal for a fluorine compound