Which of the following is most effective in coagulating positively charged hydrated ferric oxide sol ?
(i) `NaNO_(3)` (ii) `Na_(2)SO_(4)` (iii) `(NH_(4))_(3)PO_(4)`

Explanation

For the coagulation of positively charged hydrated ferric oxide sol, the coagulating powers of the anions are in the order : `PO_(4)^(3-) gt SO_(4)^(2-) gt NO_(3)^(-)`