A description that does not fit in with the application of resonance among the following is (a) Resonance is used to explain the stability of phenoxide ion. (b) Resonance is used to explain the poor reactivity of halogen in chlorobenzene. (c) Resonance is used to explain the deactivating influence of bromine in bromo benzene. (d) Resonance is used explain the neutral behaviour of benzamide.

When it comes to understanding phenoxide ion stability, the concept of resonance offers a clear and logical explanation. The phenoxide ion, created when a hydrogen atom is removed from phenol, contains a negatively charged oxygen atom. This negative charge can be delocalized across the benzene ring through the formation of several resonance structures. Such delocalization disperses the charge over a larger area, which stabilizes the molecule. Resonance structures provide a way to distribute the electron density, allowing the phenoxide ion to become more stable than it would be if the negative charge were localized on the oxygen atom alone.
It is essential for students to visualize these different resonance structures, as they depict the movement of electrons within the molecule that contributes to this stability. The more resonance forms that exist for a molecule, and the more evenly the charge is spread out, the more stable the ion will be.

The reactivity of chlorobenzene is distinctively lower than many might expect, particularly when compared to simpler organic compounds like alkyl halides. This subdued reactivity is largely attributable to resonance. In chlorobenzene, the chlorine atom is connected to a benzene ring and participates in resonance by donating a lone pair of electrons into the ring system. This electron delocalization results in the dispersion of electron density across the entire aromatic system. As a consequence, chlorine becomes less electrophilic, and the compound as a whole shows decreased reactivity towards nucleophilic substitution reactions. This contrasts with alkyl halides, in which the halogen atom does not have the same opportunity to delocalize its electrons and hence remains more reactive. Understanding this distinction is crucial for grasping the unique behavior of aromatic halogen compounds like chlorobenzene.

Reflecting on the deactivating influence of bromine in bromobenzene can help students appreciate the intricate role of substituents in organic chemistry. Being an electron-withdrawing group, bromine, through resonance, pulls electron density away from the benzene ring. Its lone pair electrons participate in the aromatic resonance, but the overall electron-withdrawing nature of bromine leads to a reduction in the electron density of the ring. This makes the ring less reactive, particularly towards electrophilic aromatic substitution reactions (EAS). Thus, bromine is considered a deactivating group, as it dampens the reactivity of the aromatic ring. Bromobenzene, therefore, is less likely to undergo further substitution reactions when bromine is present, contrasting with the behavior of an unsubstituted benzene ring that is relatively more reactive.

Exploring benzamide chemical behavior reveals that its neutral nature isn't primarily defined by resonance. Benzamide consists of an amide functional group attached to a benzene ring. While amide groups can engage in resonance, shifting electron density between the nitrogen and oxygen atoms, this interaction isn't responsible for the neutral behavior of benzamide. Instead, the neutral behavior stems from the intrinsic characteristic of the amide bond, which is a stable and generally unreactive functional group. This is markedly different from the other substituents discussed where resonance directly impacts reactivity and stability. For students, recognizing that not all behaviors in organic chemistry are attributable to resonance can prevent misconceptions and lead to a deeper, more nuanced understanding of chemical reactivity and stability.