Explain with a suitable example that the resonance structures of a molecule do not represent its real structure and are hypothetical.

(N/A) There are many organic molecules whose behavior cannot be explained by a single Lewis structure. An example is benzene. Its cyclic structure containing alternating $C-C$ single and $C=C$ double bonds is inadequate for explaining its characteristic properties.
As per the above representation, benzene should exhibit two different bond lengths due to $C-C$ single and $C=C$ double bonds. Experimentally, by $X$-ray diffraction, it is found that in benzene all $C-C$ bond lengths are $139 \ pm$.
However, as determined experimentally, benzene has uniform $C-C$ bond distances of $139 \ pm$, a value intermediate between the $C-C$ single $(154 \ pm)$ and $C=C$ double $(134 \ pm)$ bonds. Thus, the structure of benzene cannot be represented adequately by a single Kekulé structure. Benzene can be represented equally well by the energetically identical structures $(I)$ and $(II)$.
Therefore, according to resonance theory, the actual structure of benzene cannot be adequately represented by any of these structures; rather, it is a hybrid of the two structures $(I)$ and $(II)$, called resonance structures, as shown in figure $(III)$.
The resonance structures (canonical structures or contributing structures) are hypothetical and individually do not represent any real molecule. They contribute to the actual structure in proportion to their stability.