Which of the following is an acid-base indicator?
A. Vinegar

B. Lime water

C. Turmeric

D. Baking soda

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?

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

Look at Figure 5.1 which shows solutions taken in test tubes A,B,C and D. What colour is expected when a piece of red litmus paper is dropped in each test tube? Nature of the solutions is given in the table for your help.

Which of the following is an acid-base indicator?

A solution changes the colour of turmeric indicator from yellow to red. The solution is

‘Litmus’, a natural dye is an extract of which of the following?

Phenolphthalein is a synthetic indicator and its colours in acidic and basic solutions, respectively are

Turmeric is a natural indicator. On adding its paste to acid and base separately, which colours would be observed

On adding phenolphthalein indicator to a colourless solution, no change is observed. What is the nature of this solution?

Fill in the cross word given as Figure 5.2 with the help of the clues provided.

Across

(2) The solution which does not change the colour of either red or blue litmus.

(4) Phenolphthalein gives pink colour in this type of solution.

(7) Colour of blue litmus in lemon juice.

Down

(1) It is used to test whether a substance is acidic or basic.

(3) It is a natural indicator and gives pink colour in basic solution.

(5) Nature of ant’s sting.

(6) It is responsible for increase in temperature during a neutralisation reaction.