Question

In which condition blue litmus paper turns red ?
A.Acidic
B.Basic
C.Neutral
D.None of the above

Answer 1

Hint: The main use of litmus is to test whether a solution is acidic or basic . There are two types of litmus paper one is blue litmus paper and other is red litmus paper they change their colour according to the condition whether the solution is acidic or basic .

Complete step by step answer:
Litmus paper is also known as acid base indicator because it is used to distinguish between acids and bases as it changes its colour abruptly . It is made from certain lichens . There are two types of litmus paper: red litmus paper and blue litmus paper . Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions and neutral litmus paper is purple in colour .
Litmus is a water soluble mixture of different dyes extracted from lichens . It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator , used to test materials for acidity .
Litmus can also be prepared as an aqueous solution that is used similarly . Under acidic conditions , the solution is red and under alkaline conditions the solution is blue .

So, the correct answer is Option A .

Note:
Chemical reactions other than acid base can also cause a colour change to litmus paper . For example a chlorine gas turns blue litmus paper white because of the presence of hypochlorite ions . This reaction is irreversible , so the litmus is not acting as an indicator in this condition . Litmus paper is also used to test gases if the paper is dampened with distilled water before exposure to the gas .