Question

The different colors of litmus in acidic, neutral and basic solutions are respectively:
(A) Red, Orange, Blue
(B) Blue, Violet, Red
(C) Red, Colourless, Blue
(D) Red, Violet, Blue

Answer 1

Hint: The colour that is produced when litmus paper is dipped in an acidic solution has the highest wavelength amongst the colours. When pH of the solution is from 8 to 14, the litmus paper shows blue colour when dipped into it.

Complete step by step solution:
Litmus paper is a coloured paper which changes its colours depending upon the pH of the solution. So, by using the litmus paper, we can check the pH of the solution.
- Litmus paper is available as either red or blue coloured paper. When we dip it in a neutral solution, then the dye on the paper which is responsible for the colour change reacts in a way that paper turns violet. So, the colour of the litmus paper in a neutral solution is violet.
- When Litmus paper is dipped in an acidic solution, the paper turns red. This happens because there is a reaction between the dye on paper with the solution.
- Litmus paper turns blue when dipped in a basic solution. This is also a result of the reaction between the dye on paper and the basic solution.
- The dyes used here in litmus are mixtures of different dyes obtained from lichens.
So, we can conclude that litmus shows red, violet and blue colour in acidic, neutral and basic solutions respectively.

Therefore the correct answer is (D).

Note: Note that the colour change in litmus paper occurs in a range of pH 4.5 to 8.3. So, we may not see the exact red or blue colour in that range. Actually the colour produced there is a combination of both red and blue colour in different extents.