According to Graham,colloids are those substances which are

Which of the following is an emulsifier?

Which of the following is a multimolecular colloid?

This equation represents the preparation of gold sol: $2 AuCl_3 + 3 HCHO + 3 H_2 O \rightarrow 2 Au + 3 HCOOH + 6 HCl$. What type of reaction is this?

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

Consider the following statements about the Tyndall effect:
$(I)$ It is used to distinguish between a true solution and a colloidal solution.
$(II)$ It is possible only when the refractive indices of the dispersed phase and the dispersion medium differ significantly.
$(III)$ It is observed only when the size of the colloidal particles is much smaller than the wavelength of the light used.
Which of the following statements are correct?