Answer
see solution
Work Step by Step
According to the given data,
A $KCl$ solution containing 42 g of $KCl$ per 100 g of water is cooled from 60 °C to O °C.
The solubility of $KNO_3$ at 60 °C = 45 g / 100 g of water.
So, the given solution acts as an unsaturated solution at this temperature.
The solubility of $KNO_3$ at 0 °C = 27 g / 100 g of water.
At this temperature, the given solution acts as a supersaturated solution.
So, cooling down from 60 °C to 0 °C results in the recrystallization of $KCl$.