C–Cl bond of chlorobenzene in comparison to C–Cl bond in methyl chloride is

shorter and stronger

The correct answer is option 3. shorter and stronger.

Let us delve into why the \(C–Cl\) bond in chlorobenzene is shorter and stronger compared to the \(C–Cl\) bond in methyl chloride:

Chlorobenzene \((C_6H_5Cl)\)

Bond Length and Resonance: In chlorobenzene, the chlorine atom is attached to a benzene ring. Benzene is an aromatic compound with a conjugated π-electron system. The lone pairs on the chlorine atom can participate in resonance with the π-electrons of the benzene ring. This delocalization of electrons leads to a partial double bond character between the carbon and chlorine atoms. This partial double bond character results in a shorter \(C–Cl\) bond compared to a typical single \(C–Cl\) bond.

Bond Strength: The resonance delocalization also leads to an increase in bond strength. The partial double bond character makes the bond stronger because more energy is required to break a bond that has double bond characteristics compared to a single bond.

Methyl Chloride \((CH_3Cl)\)

Bond Length and Resonance: In methyl chloride, the chlorine atom is attached to a methyl group \((CH_3)\), which is a saturated hydrocarbon group with no conjugated π-electrons. The \(C–Cl\) bond in methyl chloride is a typical single bond with no resonance stabilization or partial double bond character. This results in a longer bond length compared to chlorobenzene.

Bond Strength: Without the additional stabilization from resonance, the \(C–Cl\) bond in methyl chloride is a standard single bond, which is weaker compared to the resonance-stabilized bond in chlorobenzene.

Chlorobenzene: The \(C–Cl\) bond is shorter and stronger due to resonance effects, leading to partial double bond character

Methyl Chloride: The \(C–Cl\) bond is longer and weaker because it is a typical single bond with no resonance stabilization.

Therefore, the \(C–Cl\) bond of chlorobenzene, in comparison to the \(C–Cl\) bond in methyl chloride, is: \(\text{shorter and stronger} \)