Which mixture of the solutions will lead to the formation of negatively charged colloidal [AgI]I-solution ?

Question : Which mixture of the solutions will lead to the formation of negatively charged colloidal [AgI]I^–solution ?

(1) 50 mL of 1M AgNO₃ + 50mL of 1.5 M KI

(2) 50 mL of 1M AgNO₃ + 50mL of 2M KI

(3) 50 mL of 2M AgNO₃ + 50 mL of 1.5M KI

(4) 50 mL of 0.1M AgNO₃ + 50 mL of 0.1M KI

answer : from all above options the correct answer is “(2) 50 mL of 1M AgNO₃ + 50mL of 2M KI” The reaction that will be involved in the formation of negatively charged colloidal solution is as follows: AgNO₃ + KI (excess) → [AgI]I^–  + KNO₃ As KI is maximum in case of option (2), hence, it will form negatively charged colloids. that is why we have marked option 2 for correct answer. a Point of pH where the collide particle net charge is zero is called isoelectric point of a colloid and above of this pH the particles called negatively charged and this types of collides are called negatively charged colloidal solution. and below this pH the collides are positively charged and this types of collide are called positively charged colloidal solution.