Which one of the following is not a colloidal solution?

Match the following:

List-$I$ (Sol)	List-$II$ (Method of preparation)
$A$. $As_2S_3$	$IV$. Double decomposition
$B$. $Au$	$I$. Bredig's arc method
$C$. $S$	$II$. Oxidation
$D$. $Fe(OH)_3$	$III$. Hydrolysis

The correct answer is:

In each of four separate beakers $(I, II, III, IV)$,$X \ mL$ of $y \ M \ Fe_2O_3 \cdot xH_2O$ colloidal solution is present. Equal volume and equal concentration of $KCl, K_4[Fe(CN)_6], K_3PO_4$ and $K_2SO_4$ were added into $I, II, III$ and $IV$ respectively. The efficiency of precipitation in these beakers follows the order:

The apparatus used for the precipitation of carbon particles from smoke is known as.............

The magnitude of colligative properties in all colloidal dispersions is $....$ than true solutions.

Which one of the following is a hydrophobic sol?