Explain why aryl halides are extremely less reactive towards nucleophilic substitution reactions.

(N/A) Aryl halides are extremely less reactive towards nucleophilic substitution reactions due to the following reasons:
$(i)$ Resonance effect: In haloarenes, the electron pairs on the halogen atom are in conjugation with the $\pi$-electrons of the ring. The $C-Cl$ bond acquires a partial double bond character due to resonance. As a result, the bond cleavage in haloarenes is more difficult than in haloalkanes, making them less reactive towards nucleophilic substitution.
$(ii)$ Difference in hybridisation of the carbon atom in the $C-X$ bond: In haloalkanes, the carbon atom attached to the halogen is $sp^{3}$ hybridised, while in haloarenes, it is $sp^{2}$ hybridised. The $sp^{2}$ hybridised carbon has greater s-character, is more electronegative, and holds the electron pair of the $C-X$ bond more tightly than the $sp^{3}$ hybridised carbon. Consequently, the $C-Cl$ bond length in haloarenes $(169 \ pm)$ is shorter than in haloalkanes $(177 \ pm)$. A shorter bond is harder to break, reducing reactivity.
$(iii)$ Instability of phenyl cation: In haloarenes, the phenyl cation formed by self-ionisation is not stabilised by resonance, ruling out the $S_{N}1$ mechanism.
$(iv)$ Electronic repulsions: It is difficult for an electron-rich nucleophile to approach the electron-rich arene ring.