An example of a natural indicator:
An example of a natural indicator:
The correct option is B Litmus
The explanation for the correct option:
(B) litmus: Litmus is an example of a natural indicator.
- A natural indicator is an indicator that is obtained from natural sources like plants.
- Example: Litmus is a purple dye obtained from lichens. Lichen is formed by the association of algae and fungi.
- Acid turns blue litmus to red while base turns red litmus blue.
- Other examples of natural indicators: Red cabbage, turmeric etc.
The explanation for the incorrect options:
(A) Methyl Orange: Methyl orange is an example of a synthetic indicator instead of a natural indicator. It is orange in colour and turns yellow-orange in basic or neutral medium and red in acidic medium.
- Synthetic indicators: The indicators or chemical substances that are prepared in the laboratory to indicate the acidic or basic nature of a given substance.
(C) Phenolphthalein: Phenolphthalein is an example of a synthetic indicator instead of a natural indicator. Phenolphthalein is a colourless liquid which stays colourless in an acidic medium but turns pink in a basic medium.
(D) All of the Above: As methyl orange and phenolphthalein are examples of synthetic indicators instead of natural indicators, so all of the above options is incorrect as it also includes methyl orange and phenolphthalein.
Hence, option (b) is correct.
Litmus
The explanation for the correct option:
(B) litmus: Litmus is an example of a natural indicator.
- A natural indicator is an indicator that is obtained from natural sources like plants.
- Example: Litmus is a purple dye obtained from lichens. Lichen is formed by the association of algae and fungi.
- Acid turns blue litmus to red while base turns red litmus blue.
- Other examples of natural indicators: Red cabbage, turmeric etc.
The explanation for the incorrect options:
(A) Methyl Orange: Methyl orange is an example of a synthetic indicator instead of a natural indicator. It is orange in colour and turns yellow-orange in basic or neutral medium and red in acidic medium.
- Synthetic indicators: The indicators or chemical substances that are prepared in the laboratory to indicate the acidic or basic nature of a given substance.
(C) Phenolphthalein: Phenolphthalein is an example of a synthetic indicator instead of a natural indicator. Phenolphthalein is a colourless liquid which stays colourless in an acidic medium but turns pink in a basic medium.
(D) All of the Above: As methyl orange and phenolphthalein are examples of synthetic indicators instead of natural indicators, so all of the above options is incorrect as it also includes methyl orange and phenolphthalein.
Hence, option (b) is correct.
