
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

Important Questions on Acids, Bases and Salts
If someone is suffering from the problem of acidity after overeating, which of the following would you suggest as remedy?
Lemon juice, Vinegar, Baking soda solution
Give a reason for your choice.

A white shirt has a yellow stain of curry. When soap is rubbed on this shirt during washing, the yellow stain turns red. On rinsing the shirt with plenty of water, the red stain turns yellow again.
(a) Name the natural indicator present in curry stain.
(b) What is the nature of soap (acidic or basic) as shown by the indicator present in curry stain?
(c) Name a synthetic indicator which will give pink colour with soap solution.

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