Question

One desires to prepare a positively charged sol
of silver iodide. This can be achieved by
(a) adding small amount of AgNO₃ solution to
KI solution in slight excess
(b) adding small amount of KI solution to
AgNO₃ solution in slight excess
(c) mixing equal volumes of equimolar
solutions of AgNO₃ and KI
(d) None of these

Answer 1

One desires to prepare a positively charged sol  of silver iodide. This can be achieved by  (b) adding small amount of KI solution to  AgNO₃ solution in slight excess .

- When KI solution is added to AgNO₃ solution, positively charged sol is formed due to the adsorption of Ag⁺ ions from dispersion medium.

- KI + AgNO₃ (slight excess) ⟶ AgI + KNO₃

AgNO₃ ⟶ Ag⁺ + NO₃⁻

AgI(s) + Ag+ ⟶ [AgI]Ag+

- So the correct answer is option (b).