Final Answer:
The solution that is saturated at 40°C is 4) 9 g of Ce2(SO₄)3 in 150 g of water.
Step-by-step explanation:
On a solubility graph, the point at which a solution becomes saturated indicates the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature. To determine saturation, we compare the given solutions to the solubility graph.
First, we need to identify the solubility of Ce2(SO₄)3 at 40°C. According to the graph, at 40°C, the solubility of Ce2(SO₄)3 in water is 60 g per 100 g of water. This means that 150 g of water can dissolve (60 g/100 g) * 150 g = 90 g of Ce2(SO₄)3 at 40°C.
Among the options provided, 4) 9 g of Ce2(SO₄)3 in 150 g of water is less than the calculated solubility of Ce2(SO₄)3 at 40°C (9 g < 90 g). Hence, this solution is saturated at 40°C as it contains an amount of solute within the limit of solubility at that temperature.
This result aligns with the solubility graph, confirming that 9 g of Ce2(SO₄)3 in 150 g of water forms a saturated solution at 40°C. It indicates that adding more Ce2(SO₄)3 beyond this amount to the same quantity of water at this temperature would result in excess undissolved solute, unable to further dissolve due to reaching saturation.