1) Saturated solution. A saturated solution contains the maximum amount of solute that can be dissolved at a given temperature.
1.1- Find the temperature in the chart and draw a vertical line.
Any point on the blue line shows the mass of solute in the saturated solution.
If the point is under the blue line is an unsaturated solution. If the point is above the blue line is a supersaturated solution.
1.2- Find the solutes given in the chart
NaBr (purple circle): this compound will be saturated by dissolving over 100 g at 20 ºC.
NaCl (orange square): this compound will be saturated by dissolving around 30 g at 20 ºC.
KCl (gray pentagon): this compound will be saturated by dissolving around 30 g at 20 ºC.
The answer is
Ce2(SO4)3 (green triangle): this compound will be saturated by dissolving 10 g at 20 ºC.