Answer:
90 %
Explanation:
The solubilities at 100 ÂșC and 0 ÂșC are given per 100 mL of water, so we need to calculate the solubilities for 65 mL :
5.5 g/ 100 mL x 65 mL =  3. 58 g  @ 100 ÂșC
0.53 g/ 100 mL x 65 mL = Â 0.34 Â g @ 0 ÂșC
3.4 g of acetanilide will dissove at 100 ÂșC and when cooled to  0 ÂșC it will crystallize and the amount remaining in solution will be determined by the solubilty at this temperature:
acetalinide in solution = 0.34 g
acetalinide crystallized = (3.4 - 0.34) g = 3.06 gtheoretical percent recovery = 3.06 g / 3.4 g x 100 = 90 % Â