Which of the following will coagulate starch sol?

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:

Arsenic sulfide is a negatively charged sol. Which of the following reagents has the lowest coagulating power for it?

Match the following types of colloids with their examples:

$i$. Foam	$a$. Smoke
$ii$. Gel	$b$. Cell fluid
$iii$. Aerosol	$c$. Jellies
$iv$. Emulsion	$d$. Rubber
	$e$. Froth
	$f$. Milk

Which of the following is true for a $Fe(OH)_3$ sol?

For a gold sol,the dispersed phase,dispersion medium,and the nature of the colloidal solution (lyophilic or lyophobic) are respectively ......