C-X bond length in halobenzene is smaller than C-X bond length in `CH_3-X`

Explanation

In alkyl halide (methyl chloride) halogen is attached to sp-hybridised carbon atom. But in aryl halides (chlorobenzene) halogen atom is attached to sp2 hybridized carbon-atom: Now as the size of `sp^2` hybridized orbital is smaller than sp3 hybridized orbital of carbon. So C-Cl bond in aryl halide is smaller than C-Cl bond in alkyl halides. As a result C-Cl bond in aryl halide is stronger than in alkyl halides.