Why is ferric hydroxide colloid positively charged when prepared by adding ferric chloride to hot water ?

Options

A. Due to precipitation of ferric hydroxide there is an excess of `Fe^(3+)` ions.
B. Due to preferential adsorption of `Fe^(3+)` ions by the sol of `Fe(OH)_(3)`.
C. Due to absence of any negatively charged ion.
D. Due to adsorption of `OH^(-)` and `Cl^(-)` ions, the remaining sol has only `Fe^(4+)` ions.

Answer

B

Explanation

The adsorption of positively charged `Fe^(3+)` ions by the sol of hybrated ferric oxide results in positively charged colloid.