The coagulating power of electrolytes having ions `Na^"2+" > Al^"3+" and Ba^"2+"` for arsenic sulphide sol increase in the order,

Options

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

Answer

D

Explanation

`[AS_2S_3] S^(2-)` is negative charged sol.
According to the Hardy Suhulze rule, The greater the change on the cation (oxidation state), the greater is its coagulating power for the negatively charged sol. Hence, the increasing order is:
`Na^(+) < Ba^(2+) < Al^(3+)`
`Al^(3+) "(highest coagulating power)".`