Answer:
See explanation
Step-by-step explanation:
The bonding in certain compounds or ions can not be thoroughly explained in terms of a single Lewis structure.
The observed properties of the compound or ion indicate that it can not be entirely represented by a single Lewis structure. For example, all C-C bond in benzene are equal.
When this is the case, a number of structures called resonance structures are invoked in order to satisfactorily explain the properties of the particular chemical specie under study.