Explain why resonance structures are used instead of Lewis structure to correctly model certain molecules

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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.

organisms are more likely to be more preserved in mud than sand because mud is moist and wet, while sand is very dry.