Question

The dispersed phase in colloidal iron (III) hydroxide and coltoidal gold is positively and negatively charged, respectively. Which of the following statements is not correct?

• A. Sodium sulphate solution causes coagulation in both sols
• B. Magnesium chloride solution coagulates, the gold sol more readily than the iron (III) hydroxide sol.
• C. the processes of electrophoresis provide charge on both the sols
• D. Colloidal iron is coagulated by $M{g}^{+2}$ and coltoidal gold is coagulated by $C{l}^{-}$

Answer 1

The correct option is D Colloidal iron is coagulated by $M{g}^{+2}$ and coltoidal gold is coagulated by $C{l}^{-}$

Since, dispersed phase of colloidal iron $\left(III\right)$ hydroxide is positively charged, colloidal iron can't be coagulated by positive ion $M{g}^{+2}$ because positively charged iron hydroxide colloidals repel $M{g}^{2+}$ ion. In the same way, negatively charged gold colloids can't be coagulated by anion $C{l}^{⊝}$. Therefore, the statement D is not correct.