The correct order of coagulating power of the following ions to coagulate the positive sol is

$$\mathrm{\mathop {{{[Fe{{(CN)}_6}]}^{4 - }}}\limits_I ,\mathop {C{l^ - }}\limits_{II} ,\mathop {SO_4^{2 - }}\limits_{III}}$$

The macromolecular colloids of the following are

I. Starch solution

II. Sulphur sol

III. Synthetic detergent

IV. Synthetic rubber

Assertion (A) Animal skins are colloidal in nature.

Reason (R) Animal skin has positively charged particles.

The diameters range of colloidal particles is approximately.