Which of the following substances show the highest colligative properties?

In two separate experiments, the same quantity of electricity was passed through silver and gold solutions. [Assume ' $l$ ' constant]. The amounts of Ag and Au deposited are 2.15 and 1.31 g , respectively. The valency of gold is

[atomic mass of $\mathrm{Ag}=107.9$; $\mathrm{Au}=197$ ]

Which of the following is a zero order reaction?

The coagulation of 200 mL of a positive colloid took place when 0.73 g of HCl was added to it without changing the volume much. The flocculation value of HCl for the colloid is