Which is correct order of coagulation of ion necessary for coagulation of calloid sol ?

The correct order of coagulation of ion necessary for coagulation of colloid sol is (d) Trivalent ion < divalent ion < monovalent ion. This order follows the principle of electropherosis, which states that the valence and hence the charge of an ion will determine the speed of its migration through the electrified solution. Trivalent ions, like ferric chloride, effectively carry a more positive charge than monovalent and divalent ions, so they will migrate more quickly. Divalent ions, like calcium chloride, carry a less positive charge than trivalent ions, so they will migrate slower, and monovalent ions, like sodium chloride, will be the slowest.