Question

Most effective coagulant for a colloidal solution of arsenic sulphide in water is:

• A. $0.1M$ sodium phosphate
• B. $0.1M$ zinc sulphate
• C. $0.1M$ zinc nitrate
• D. $0.1M$ aluminium chloride

Answer 1

The correct option is A $0.1M$ sodium phosphate

Most efficitive coagulant for a collodial solution can be identified by using Hardy Schulze law. It states that greater in the valency of the oppositely charged ion of the electrolyte being added the faster is the coagulation.

$\to$ Here Arsenic sulphide collodial solution in water in negative so it needs highest positive charged element.

$\to$ Aluminium chloride $\left({Al}^{+3}\right)>$ all other elements given

Ans :- Option A.