\(o\)-dichlorobenzene has a higher dipole moment due to a lower bond angle than the \(m\)-isomer. Hence, the order of increasing dipole moment is :
\(p\)-dichlorobenzene \(\,<\, m\)-dichlorobenzene \(\,<\, o\)-dichlorobenzene
$NO_2^-, NO_3^-,NH_2^- , NH_4^+ , SCN^-$