Which of the following is responsible for the stability of hydrophilic sols?

Lyophilic sols are more stable than lyophobic sols because their particles are

Which of the following is a multimolecular colloid?

Milk is a colloidal sol of ........

$A$ $42.12 \% (w/v)$ solution of $NaCl$ causes precipitation of a certain sol in $10 \, hours$. The coagulating value of $NaCl$ for the sol is $.....$
[Given : Molar mass : $Na = 23.0 \, g \, mol^{-1} ; Cl = 35.5 \, g \, mol^{-1}]$

$A$ colloidal solution can be purified by