Why nitrogen is important for the plants?

Explanation

Haloarenes are less reactive than haloalkanes:
(1) Resonance effect : In haloarenes, the electron pairs on the halogen atom are in conjugation with µ-electrons of the ring and the following resonating structures are possible:

As a Result of Resonance, there is delocalisation of electron on C - Cl bond with aquires a partial double bond character. This is also evident form the contribution of structure III, IV, and V. As a result, tlie bond cleavage in haloarenes is difficult than haloalkanes in which carbon is attached to halogen by a pure single bond. Therefore haloarenes are less reactive to wards nucleophilies substitution reactions.
(2) Difference in hybridisation states of carton atom in C-X bond : In haloalkanes the carbon atom of the C - X bond is `sp^3` hybridised while in haloarenes the carbon atom attached to halogen is `sp^2` hybridised. The `sp^2` hybridised carbon atom with a greater s-character is more electronagtive. It can hold together the electron pair of the bond more tightly than the `sp^3` hybridised carbon atom in alkyl halides with less s-character. Therefore, the C - X bond in haloarenes is shorter than in haloalkanes. The shortening the bond length imparts stabili1y to aryl halides and as a result, the bond cleavage become rather difficult. Therefore haloarenes are less reactive than haloalkanes towards nucleophilies substitutions.