The coagulating power of electrolytes having ions `Na^(+), Al^(3+) and Ba^(2+)` for arsenic sulphide sol increases in the order-

Options

A. `Al^(3+) lt Ba^(2+) lt Na^(+)`
B. `Na^(+) lt Ba^(2+) lt Al^(3+)`
C. `Ba^(2+) lt Na^(+) lt Al^(2+)`
D. `Al^(3+) lt Na^(+) lt Ba^(2+)`

Explanation

According to Hardy-Schulze rule, coagulating power of electrolyte varies directly with the valency of the ion causing coagulation. In the coagulation of negatively charged arsenic sulphide sol, the order of coagulating power is `Na^(+) lt Ba^(2+) lt Al^(3+)`