Question

The ratio of a number of moles of AgNO₃, Pb(NO₃)₂ and Fe(NO₃)₃ required for coagulation of a definite amount of colloidal sol of silver iodide prepared by mixing AgNO₃ with an excess of KI will be:

(a) 1:2:3
(b) 3:2:1
(c) 6:3:2
(d) 2:3:6

Answer 1

Correct option is (c) 6:3:2

With excess KI, colloidal particles will be [AgI]I^–.

Molar ratio required for coagulation of same amount of [AgI]I^– is 1 : 1/2 : 1/3 = 6 : 3 : 2.