Why are aryl halides less reactive towards nucleophilic substitution reactions than alkyl halides? How can we enhance the reactivity of aryl halides?

(N/A) Aryl halides are less reactive towards nucleophilic substitution than alkyl halides due to the following reasons:
$1$. Resonance Effect: The lone pair of electrons on the halogen atom participates in conjugation with the $\pi$-electrons of the benzene ring,resulting in a partial double bond character between the carbon and the halogen atom. This makes the $C-X$ bond stronger and shorter,making it difficult to break.
$2$. Difference in Hybridization: In aryl halides,the carbon atom attached to the halogen is $sp^2$-hybridized,which is more electronegative and holds the electron pair more tightly than the $sp^3$-hybridized carbon in alkyl halides.
$3$. Instability of Phenyl Cation: The phenyl cation formed by the self-ionization of aryl halides is not stabilized by resonance.
$4$. Electron Repulsion: The electron-rich benzene ring repels the incoming nucleophile.
To enhance the reactivity of aryl halides,we can introduce electron-withdrawing groups (like $-NO_2$) at the ortho and para positions. These groups withdraw electron density from the benzene ring,thereby facilitating the attack of the nucleophile.