Dorji has a few bottles of soft drink in his restaurant. But, unfortunately, these are not labeled. He has to serve the drinks on the demand of customers. One customer wants acidic drink; another wants basic and third one wants neutral drink. How will Dorji decide which drink is to be served to whom?

Since the drinks are edible, Dorji can take decision by testing the drinks. Acidic drinks will be sour in taste whereas basic drinks will be bitter in taste and neutral drinks will have no taste.

Dorji can decide which drink is acidic by taking the litmus test:

(i) If drink turns blue litmus paper to red, then it is acidic in nature and hence it will be served to first customer who wants acidic drink.

(ii) If drink turns red litmus paper to blue, then the drink is basic and hence it will be served to another customer who wants basic drink.

(iii) If drink does not show change in colour, then it will be neutral drink and hence it will be served to third customer who wants neutral drink.