Concentration of the tlc sample is very important. for liquid compounds (like benzyl alcohol), just the compound then a few drops of solvent. for solid compounds (like benzoic acid), just the compound and dissolve it in the solvent. a. use 1 drop of; cover the tip of your spatula with b. use 1 l of; use 5.0 g of c. pour a little of; use one large scoop of d. use 1 ml of; use 0.5 g of