Dipole moment is highest for

As the number of chlorine atoms increases symmetrical nature increasesμ of CH3Cl > CH2Cl2 > CHCl3 > CCl4Alternate explanation...CCl4 is a symmetrical molecule with zero dipole moment. CH3Cl,CH2Cl2,CHCl3 have distorted tetrahedral shape .As the number of 'Cl' atoms increases repulsions between bond pairs increases thus bond angle (θ) increases ,dipole moment decreases.