For coagulating `As_(2)S_(3)` colloidal sol, which of the following will have the lowest coagulation value

Options

A. `NaCl`
B. `KCl`
C. `BaCl_(2)`
D. `AlCl_(3)`

Answer

D

Explanation

The amount of electrolyte required to coagulate a fixed amount of a solution depends upon the valency of flocculation ion. The flocculating power of the various ions follows the following order, larger the valency lesser will be coagulation value. `Al^(3+) gt Mg^(2+) gt Na^(+)` hence lowest coagulation value is of `AlCl_(3)`.