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The C-Cl bond length in chlorobenzene is **shorter** (169 pm) than in methyl chloride (177 pm) because:
AChlorobenzene has more electrons
BChlorine atoms shrink in the aromatic ring
CThe carbon in chlorobenzene is sp² hybridised (more s-character → more electronegative, holds C-Cl bond tighter); additionally, resonance gives partial C=Cl character
DChlorobenzene is smaller
Answer & Solution
Correct answer: C. The carbon in chlorobenzene is sp² hybridised (more s-character → more electronegative, holds C-Cl bond tighter); additionally, resonance gives partial C=Cl character
**sp² (33% s-character)** vs **sp³ (25% s-character)**: sp² carbon is **more electronegative and forms a shorter bond**. **Resonance** also imparts partial **C=Cl double-bond character**. Hence the C-Cl bond in haloarene is **shorter and stronger** than in haloalkane → less reactive to nucleophilic substitution.
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