Identify the three isomeric chlorotoluenes having dipole moments: 1.35D, 1.9D and 1.78D.

Explanation

Methyl group `(-CH_(3))` can exert a +I effect while Cl-atom exedrt -I effect. In p-chlorotoluene, `-CH_(3)` and `-Cl` group moments act linearly. So its dipole moment is equal to the sum of the of the two group moments. Hence, dipole moment of this compound is maximum. `-CH_(3)` group moment is considered to act in the direction of the ring. so in m-chlorotoluene, these two group moments act at an angle `60^(@)`. hence, dipole moment of m-chlorotoluene, these two group moments act at an angle of `120^(@)` and hence the dipole moment of this isomer is less than tha tof the m-isomer. thus, dipole moments of 1.35D, 1.78D and 1.90D correspond to o-, m- and p-chlorotoluenes.