I think the answer is (3) cathode - because more positively charged ion in the electrolyte is having less coagulating capacity in the given order so it means that dispersed phase must be positively charged. so positively charged dispersed phase will move towards negatively charged cathode.

Introduction:
Electrophoresis is a technique used to separate and analyze charged particles in a solution. It works on the principle that charged particles will migrate towards the electrode of opposite charge when an electric field is applied.

Coagulation Power of Electrolytes:
The coagulation power of an electrolyte refers to its ability to cause the coagulation or precipitation of colloidal particles in a solution. In the given order, Na3PO4 has the highest coagulation power, followed by BaSO4, and then AlCl3.

Explanation:
When an electric field is applied in electrophoresis, the dispersed phase particles in a colloidal solution will migrate towards the electrode of opposite charge. This migration is based on the charge on the particles and the charge on the electrode.

Effect of Coagulation Power:
The coagulation power of an electrolyte determines the degree of coagulation or precipitation of colloidal particles. Higher coagulation power means a greater ability to neutralize and destabilize the charged particles, leading to their coagulation and precipitation.

Order of Coagulation Power:
1) Na3PO4: This electrolyte has the highest coagulation power among the given options. Therefore, in electrophoresis, the dispersed phase particles will migrate towards the anode, which is positively charged. The positively charged particles will be attracted to the negatively charged electrode.

2) BaSO4: BaSO4 has a lower coagulation power compared to Na3PO4. In electrophoresis, the dispersed phase particles will still migrate towards the anode, but the degree of migration may be less compared to the effect of Na3PO4.

3) AlCl3: AlCl3 has the lowest coagulation power among the given options. In electrophoresis, the dispersed phase particles may migrate randomly or show minimal migration towards either electrode. The lower coagulation power of AlCl3 means it has a weaker effect on destabilizing the charged particles, resulting in less migration.

Conclusion:
In electrophoresis, the dispersed phase particles in a colloidal solution will migrate towards the electrode of opposite charge. The order of coagulation power of the electrolytes determines the migration pattern. In the given order, Na3PO4 has the highest coagulation power, causing the particles to migrate towards the anode. BaSO4 has a lower coagulation power, leading to partial migration towards the anode. AlCl3 has the lowest coagulation power, resulting in random or minimal migration.