You have been provided with three test tubes. One of them cotains distilled water and the other two cotain 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 tube ?

Explanation

(a) Number the test tubes as 1, 2 and 3.
(b) Take three red litmus paper strips and dip each one in the test tubes and observe the colour change. The solution in which it turns blue is a basic solution.
(c ) Now add few drops of this basic solution to the other two test tubes.
(d) Now dip the red litmus paper in the other two test tubes.
(e) The one that changes to blue is distilled water and the other which does not show any change to red litmus paper is acidic solution.