Question

Which mixture of the solutions will lead to the formation of negatively charged colloidal [Agl]I^– sol ?

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

(2)  50 mL of 1 M AgNO₃ + 50 mL of 2 M KI

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

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

Answer 1

According to NTA official Answer key The answer will be

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

(2) 50 mL of 1 M AgNO3 + 50 mL of 2 M KI

Answer 2

Correct option  (2) 50 mL of 1 M AgNO₃ + 50 mL of 2 M KI

Explanation:

Generally charge present on the colloid is due to adsorption of common ion from dispersion medium. Millimole of KI is maximum in option (2) (50 x 2 = 100) so act as solvent and anion I^– is adsorbed by the colloid AgI formed