To determine how many grams of CuSO4 will dissolve in 100 grams of water at 90°C, you would need to refer to the graph you mentioned, which shows the solubility of various solid ionic compounds at different temperatures.
Since I am unable to see the graph, I cannot provide the exact answer. However, by examining the graph you refer to, you should look for the data point corresponding to CuSO4 at 90°C, which will indicate the solubility in grams per 100 grams of water.
Once you find that value on the graph, you can select the correct answer from the provided options (35 g, 40 g, 55 g, or 63 g). If you can provide the solubility value from the graph, I can help you confirm the answer.