Q.State whether the $\text{C--Cl}$ bond in chlorobenzene is shorter or longer, and stronger or weaker, than the $\text{C--Cl}$ bond in a chloroalkane, and give the structural reason.

In chlorobenzene, chlorine's lone pair conjugates by resonance with the ring's $\pi$ system (possible because the halogen sits on an $sp^2$ carbon whose $p$ orbital is aligned for overlap), giving the $\text{C--Cl}$ bond partial double-bond character; a bond with some double-bond character is both shorter and stronger than a pure single bond. This effect has no counterpart in a saturated chloroalkane, where the halogen-bearing carbon is $sp^3$ and there is no adjacent $\pi$ system to conjugate with, so that $\text{C--Cl}$ bond remains a essentially pure, longer, weaker single bond. The greater s-character of the sp2 ring carbon's bonding orbital reinforces …

Connect 'shorter' and 'stronger' to the same underlying cause (partial double-bond character from resonance) rather t …

Reasoning only from 'chlorine is more tightly held because the ring is electron-poor' -- the correct mechanism is resonance donation giving p …