Which of the following electrolytes would be most effective in the coagulation of Arsenic sulphide sol?

The following data is obtained for coagulating a positively charged sol in $2$ hours:

Conc. of $Cl^{-}$ in $mol \cdot L^{-1}$	Result
$5 \times 10^{-5}$	Sol not precipitated
$6 \times 10^{-5}$	Sol not precipitated
$7 \times 10^{-5}$	Sol precipitated
$8 \times 10^{-5}$	Sol precipitated
$1 \times 10^{-4}$	Sol precipitated

What is the coagulating value of electrolyte for this sol?

What type of reaction is used to obtain $Au$ (sol)?
Reaction: $2AuCl_3 + 3HCHO + 3H_2O \rightarrow 2Au (sol) + 3HCOOH + 6HCl$

Label the hydrophilic and hydrophobic parts in the following compounds.
$(i)$ $CH_3(CH_2)_{10}CH_2OSO_3^-Na^{+}$
$(ii)$ $CH_3(CH_2)_{15}N^{+}(CH_3)_3Br^{-}$
$(iii)$ $CH_3(CH_2)_{16}COO(CH_2CH_2O)_nCH_2CH_2OH$

On addition of $1 \, mL$ solution of $10\% \, NaCl$ to $10 \, mL$ gold sol in the presence of $0.25 \, g$ of starch,the coagulation is just prevented. What is the gold number of starch?

Among the colloids cheese $(C)$,milk $(M)$ and smoke $(S)$,the correct combination of the dispersed phase and dispersion medium,respectively is