QUESTION 7 In recrystallization of benzoic acid, which of the following impurities (trace amount) will be removed least effectively during the hot filtration step? a. Sodium chloride. b. Yellow dye. c. Sand. d. Decolorizing carbon. QUESTION 10 The following are selected steps of the procedure for collecting crystals from a recrystallization mixture via suction filtration. Which step should always be carried out while the vacuum is turned off? a. Wash the crystals collected on the Buchner funnel with two 3-5 mL portions of cold solvent. b. Spread a small amount of solvent to wet a piece of filter paper that covers all the holes in the Buchner funnel. c. Partially air dry the crystals collected on the Buchner funnel. d. Pour the recrystallization mixture slowly in the middle of the Buchner funnel covered with the filter paper.