【Daily Question】Chemical Analysis Edition, 2019.9.15

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This post was last edited by zjp on 2019-9-15 07:42. Multiple-choice question: When preparing a 0.1 mol L-1 NaOH standard solution, which of the following preparation methods is incorrect? (M=40 g/mol). A. Prepare a saturated solution of NaOH, store it in a polyethylene plastic bottle, keep it sealed until the solution becomes clear; then take 5 ml of this clear solution and add it to 1 liter of water free of CO2, stir well, and store the mixture in a colorless reagent bottle. B. Dissolve 4.02 grams of NaOH in 1 liter of water, heat while stirring, and store the solution in a ground-glass flask. C. Dissolve 4 grams of NaOH in 1 liter of water, heat while stirring, and store the solution in a colorless reagent bottle. D. Dissolve 2 grams of NaOH in 500 ml of water, heat while stirring, and store the solution in a colorless reagent bottle. B