Final answer:
Resonance forms are not in equilibrium; they are conceptual tools representing the delocalization of electrons that cannot be adequately described by one single Lewis structure. The true form of a molecule is the resonance hybrid, an average of all resonance forms.
Step-by-step explanation:
The statement that resonance forms are in equilibrium with each other is false. Resonance forms are not individual species that exist independently and interconvert into each other. Instead, they are imaginary constructs used to represent a single structure that cannot be adequately described by a single Lewis structure. Resonance forms are meant to represent the delocalization of electrons within a molecule. For instance, benzene's resonance structures depict the electron distribution among the carbon atoms, suggesting delocalization throughout the ring, not an actual interchange between the two forms.
A better description of resonance comes from the concept of a resonance hybrid, which is an average of the various resonance forms shown by the individual Lewis structures. In reality, the molecule exists as this hybrid, and the electrons are delocalized in a way that is more accurately described by molecular orbital theory rather than jumping back and forth between resonance forms.