Question

the CCl bond length in chlorobenzene is shorter that in CH3Cl

Answer 1

The carbon in C-Cl bond in chlorobenzene is sp2hybridised, while in CH3-Cl is sp3 hybridised. In sp2hybrid orbitals have more of s -character and hence the carbon if chlorobenzene withdraws the electron pair between C-Cl with greater force. As a result, C-Cl bond is shorter than CH3-Cl.