Question

(a) What is a universal indicator? For what purpose 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?

Answer 1

(a) Universal indicator is used to detect whether the given solution is an acid or a base and when it is dipped in any of the solutions it changes its colours and informs us the type of solution and it is also a pH indicator and can be also used to detect the strength of the solution

(b) In acidic medium, the indicator will show colours like red, orange, yellow, orangish yellow etc and with the help of a pH scale, we can determine the strength.

in a basic medium, the indicator will change its colour to blue-violet or purple and with the help of a pH scale, we can determine the strength.

In a neutral medium, it will change its colour to green.

(c) A neutral substance is neither an acid nor a base. Water is a neutral substance and so it turns the universal indicator solution to green.