The dispersed phase in colloidal iron (III) hydroxide and collodial gold is positively and negtively charged respectively with of the following statement is not correct ?

Options

A. Sodium sulphate solution causes coagulation in both sols
B. Mixing the sols has no effect
C. Coagulation in both sols can be brought about by electrophoresis
D. Magnesium chloride solution coagulates the gold sol more readily than the iron `(III)` hydoxide sol.

Answer

B

Explanation

Oppositely charged sols when mixed in almost equal proportions, neutralize their charges and get partially or competely precipitiated. Mixing of hydrated ferric oxide (+ve sol) and gold sol `(-"ve sol")` bring them in the precipitated forms. This type of coagulation is called mutual coagulation. Magnesium chloride provides `Mg^(2+)` to coagulate the gold sol but provides `Cl^(-)` to coagulate the ferric hydroxide sol.