$A$ colloidal solution is subjected to an electric field,and the colloidal particles move towards the anode. The amount of electrolytes $BaCl_{2}$,$AlCl_{3}$,and $NaCl$ required to coagulate the given colloid is in the order:

What type of colloid is fog?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Finest gold is red in colour,as the size of the particles increases,it appears purple then blue and finally gold.
Assertion $R$: The colour of the colloidal solution depends on the wavelength of light scattered by the dispersed particles.
In the light of the above statements,choose the most appropriate answer from the options given below:

Oils and fats are obtained by saponification of potassium stearate. Its formula is $CH_3(CH_2)_{16}COO^-K^+$. The hydrophobic end of the molecule is $CH_3(CH_2)_{16}$ and the hydrophilic end is $COO^-K^+$. Potassium stearate is an example of:

The size of colloidal particles is . . .

Assertion : $Fe^{3+}$ can be used for coagulation of $As_2S_3$ sol.
Reason : $Fe^{3+}$ reacts with $As_2S_3$ to give $Fe_2S_3$.