The ion that is more effective for coagulation of sol is:
Hardy Schulze Rule -
According to it, "Higher the valency of the active electrolyte ion, the more is its power to precipitate the sol."
is negatively charged sol. Hence,
is the most effective coagulating agent as the higher is the magnitude of positive charge, the higher is the coagulating power.
Therefore, the option number (2) is correct.
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