Which can adsorb larger volume of hydrogen gas?

A colloidal solution is subjected to an electric field than colloidal particles more towards anode. The amount of electrolytes of $$\mathrm{BaCl}_2, \mathrm{AlCl}_3$$ and $$\mathrm{NaCl}$$ required to coagulate the given colloid is in the order

Zeta potential is

A sol of $$\mathrm{AgI}$$ is prepared by mixing equal volumes of $$0.1 \mathrm{~M} \mathrm{~AgNO}_3$$ and $$0.2 \mathrm{~M} \mathrm{~KI}$$, which of the following statement is correct?