An increase in the temperature increases the dissolution as it is easy to break the bonds of sugar at a higher temperature and dissolution is an endothermic process.

Powdered sugar dissolves faster in water, as the surface area of contact of the sugar molecules with water increases i.e. more molecules come in the contact with the molecules of water.

Thus, powdered sugar in hot water dissolves rapidly than other conditions.

Thus, Option (iv) is the correct.