Which is $NOT$ an example of a macromolecular colloid?

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?

Milk is an example of

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:

$A$ fresh precipitate can be transformed into a colloidal mixture by -

Which one of the following is most effective in causing the coagulation of an $As_2S_3$ sol?