Which of the following is a multimolecular colloid?

$100 \ mL$ of $0.0018\%(w/v)$ solution of $Cl^{-}$ ion was the minimum concentration of $Cl^{-}$ required to precipitate a negative sol in one $h$. The coagulating value of $Cl^{-}$ ion is $.......$ (Nearest integer).

Which one of the following sols acts as a lyophilic colloid?

The most suitable electrolyte for the coagulation of arsenic sulphide sol will be

Arrange the following electrolytes in the increasing order of coagulation power for the coagulation of $As_2S_3$ sol.
$\mathop {K_2SO_4}\limits_{(I)}$ $\mathop {CaCl_2}\limits_{(II)}$ $\mathop {Na_3PO_4}\limits_{(III)}$ $\mathop {AlCl_3}\limits_{(IV)}$

According to Graham,colloids are those substances which are