AP EAMCET Engineering 23 Sep 2020 Shift 1 Paper

The colloidal sol of Fe(OH)3 has positive charge, due to the preferential adsorption of ferric ions Fe3+ on the surface of the ferric hydroxide particles.
Fe(OH)3+Fe3+⟶Fe(OH)3Fe3+
Hence, during electrophoresis of colloidal sol of Fe(OH)3, the colloidal particles move towards cathode, whereas the dispersion medium migrates in the direction opposite to those of particles.