a 16.5% b. 16.7% 18. What is the percent by mass concentration of a solution that contains 6g of sugar dissolved in 20.7g of water? a 21.21% b. 22.21% c. 22.47% d. 22.74% 19. What is the volume of a 20% methyl solution that contains 15mL of methyl? a 6 mL of methyl b. 5 mL of methyl c. 4 mL of methyl d. 3 mL of methyl 20. A solution of benzene and toluene was prepared by adding toluene to benzene until the total volume becomes 135mL. By volume, the solution is 30% benzene. How much benzene, in mL, is in the solution? a 39.5 mL of benzene b. 40.5 mL of benzene c. 41.5 mL of benzene d. 42.5 mL of benzene​