(a). What is a universal indicator? For what purrpose is it used?
(b). How does a universal indicator work?
(c). Water is a neutral substance. What colour will you get when you add a few drops of universal indicator to a test-tube containing water?

What is universal indicator?

(i) Define universal indicator. For what purpose it is used? (ii) Two solutions A and B have pH values of 3.0 and 9.5 respectively. Which of these will turn litmus solution from blue to red and which will turn phenolphthalein from colourless to pink? (iii) What is a neutral substance. WHat colour will you get when you add a few drops of universal you get when you add a few drops of universal indicator of a test tube containing distilled water?

What happens when you blow air into a test tube containing lime water?

What colour would hydrochloric acid (pH = 1) turn universal indicator '?

What is the colour of universal indicator in very basic solutions?

Add few drops of hibiscus indicator in soap solution. What do you observe ?

To check the pH of tap water and compare it with pH of the water in the local water body. Apparatus : Test tubes or beaker Materials : Universal pH indicator / litmus paper Procedure : implies Take water sample from tap of your home in a test tube. implies Add few drops of the universal indicator into the test tube containing tap water. implies Observe the water sample in the test tube for colour change. implies Test pH using a litmus paper, in the water sample placed in a beaker. implies Dip the litmus paper into the water in the local water body. implies Observe colour changes of the litmus paper. Observation : implies Test tube containing tap water, turns yellow colour with addition of pH indicator. implies Litmus paper does not show colour change with tap water. implies Water sample collected from pond shows red colour with pH indicator. Litmus paper turns red as it is dipped in water of local water body. Conclusion : The uncontaminated tap water is neutral while water of local water body is acidic. Can you say whether the water is polluted or not on the basis of your observations?