Question

(A) toluene, (B) m-dichlorobenzene, (C) o-dichlorobenzene and (D) p-dichlorobenzene in order of increasing dipole moment is ________.

Answer 1

Due to symmetry, p-dichlorobenzene have zero dipole moment while o-dichlorobenzene have highest dipole moment.
m-dichlorobenzene have dipole moment lower that ortho due to $120$ degree angle between two dipoles.
so order is
$D<A<B<C$