Chemistry - CHEMICAL BONDING Question with Solution | TestHub

* The reference molecule is chlorobenzene, which has a net non-zero dipole moment ($\mu >0$) due to the single polar C–Cl bond.

* 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, and hexachlorobenzene are highly symmetrical structures.

* In these three symmetrical molecules, the individual C–Cl bond dipoles completely cancel each other out, resulting in a net dipole moment of zero ($\mu =0$).

* In contrast, 1,2,3-trichlorobenzene is asymmetrical, causing its bond dipoles to reinforce each other and create a dipole moment greater than chlorobenzene.

* Therefore, exactly 3 molecules have a dipole moment less than chlorobenzene.