Question

From which plant is litmus paper or litmus solution obtained ?
(A) Moss
(B) Rose
(C) Hibiscus
(D) Lichen

Answer 1

Hint: Litmus paper is an indicator to know whether a substance is acidic, basic or neutral. It comes in two, red and blue colours. Blue litmus paper will turn into red when it is put in acidic medium and red litmus paper will turn into blue when it is put in the basic medium.

Complete answer:
Let us now know, what is the composition, source and the process to obtain the litmus.
Litmus is a water soluble mixture of different dyes extracted from lichens. Litmus solution is extracted from lichens. Lichens are plants which belong to the Thallophyta group. To obtain litmus solution, the crushing and grinding of lichens are done. The dyes are then added to neutral water to get the required litmus solution.
Litmus paper is made from wood cellulose like most of the paper composition. The wood is treated with solutions prior to paper manufacturing in order to remove resinous material and lignin from the wood. The ability of litmus paper to change colour when exposed to an acid or base is a result of litmus paper being infused with lichens then the paper is dried and packaged.

Hence, the correct answer is (D) Lichen.

Note: It is important to note that if the red litmus paper does not change its colour when put in a solution then the solution is acidic. Similarly, if blue litmus paper does not change its colour then the solution we put it in is a basic solution.