You are given three test tubes. The three test tubes contain distilled water, an acidic solution and the basic solution, respectively. There is only red litmus paper available in order to identify what is there in each test tube. How will you find out what is in each of the test tubes?

Using red litmus paper, we can determine what is in each test tube. This can be obtained by observing the red litmus paper\’s change in colour.

The three test tube solutions are poured one at a time on litmus paper.
A basic solution can be found in the substance that changes red litmus into blue.
Divide the blue litmus paper into two equal pieces.

The acidic solution will be the one in the test tube that causes the blue litmus paper to become red.
Water is present in the test tube\’s solution, which does not affect the colour of the red or blue litmus paper.

Distilled water has a pH of 7 after being immediately distilled. But shortly after distillation, it takes up carbon dioxide from the air and has a pH of 5.8, making it mildly acidic.