Question

The natural indicator litmus is extracted from:
A.Beetroot
B.China rose
C.Lichens
D.Tumeric

Answer 1

Hint: We know that indicators are substances that show changes in colour due to change in pH. They are known as acid-base indicators. They are generally acid (or) bases whereas their conjugate base (or) acid forms show various colours because of the difference in their absorption spectra. In our day to day life, we use substances like lemon, common salt, vinegar and salt. They have different properties and the major difference between them is whether they are acidic (or) basic.

Complete step by step answer:
We use natural acids such as curd, lemon juice, vinegar and orange juice. These substances have sour taste and their chemical nature is acidic.
Substances such as baking soda do not have sour taste but they are bitter. It feels soapy and due to this they are known as bases. The chemical nature of soapy and bitter substances is basic.
Indicators are substances that are used to check if a substance is acidic (or) basic. When added to a solution comprising an acidic (or) basic, the indicators change their colour.
Litmus, china rose petals, turmeric are some of the naturally occurring indicators.
Anthocyanin is present in china rose petals. Option (B) is incorrect.
Beetroot and turmeric are also natural indicators, but litmus is not extracted from them. So Option (A) and (D) are incorrect.
The natural indicator litmus is extracted from lichens. Blue litmus turns red in acids and in base, red changes to blue.

$\therefore $Option (C) is correct.

Note: Litmus appears in purple colour in distilled water. We can use it in the form of solution (or) as strips of paper known as litmus paper. Red and blue litmus are the two colours of litmus paper. Solution such as detergent solution, solution of soap, common salt, shampoo, solution of sugar, solution of baking soda are mixed with water, we can observe that these solutions does not show any colour change in red (or) blue litmus. Such solutions are called neutral solutions and they are neither acidic (nor) basic.