3. 20% by mass means ; 20% by volume means a. 20 g solute in 80 g solution; 20 mL solute in 80 mL solution. b. 20 g solute in 100 g solvent; 20 mL solute in 100 mL solvent. c. 20 g solute in 100 g solution; 20 mL solute in 100 mL solvent. g d. 20 g solute in 100 g solvent; 20 mL solute in 100 mL solution​