(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?

Explanation

(i) Universal indicator is a mixture of many different indication (or dyes) which give different colours at different pH values of the entire pH scale. The colour produced by universal indicator is used to find the pH value of acid or base by matching the colour with the colours on pH colour chart.
(ii) Solution A is acidic and will turn litmus solution from blue to red.
Solution B is basic and will turn phenolphthalein from colourless to pink.
(iii) Green colours will be obtained.