Question

You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test?

Answer 1

Using red litmus paper, we can determine the contents of each test tube. This can be accomplished by observing the color shift of the red litmus paper:

• A few drops of each of the 3 samples in the test tubes are added separately to the litmus paper.
• A basic solution in one of the test tubes turns red litmus paper blue.

• Separate the blue litmus paper into two halves and a few drops of each of the remaining 2 samples in the test tubes should be added separately to the blue litmus paper.
• Now, the acidic solution will be the solution in the test tube that turns blue litmus paper red.
• Distilled water is present in test-tube solutions that do not change the color of either red or blue litmus paper.