Identify the negatively charged sol from the following.

Sodium stearate forms in water:

The coagulation of $100 \, mL$ of a colloidal sol of gold is completely prevented by the addition of $0.25 \, g$ of a substance '$X$' to it before adding $10 \, mL$ of $1 \% \ NaCl$ solution. The gold number of '$X$' is:

Which of the following is correctly matched?

The minimum quantity of sodium chloride which is necessary to precipitate $10 \ L$ of sol in two hours is $0.585 \ g$. The flocculation value of sodium chloride is

In the process of peptization,......