Three identical test tubes contain water, sodium hydroxide solution and sulfuric acid solution. How to distinguish the contents of tubes using one indicator?
Add a few drops of an indicator solution, such as litmus, to each tube. In a test tube with a solution of sulfuric acid, the color of the litmus will turn red, in a test tube with a solution of sodium hydroxide – blue, in a test tube with water the color will not change.
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