Blue litmus when added to an acidic solution changes to-

The litmus paper test is used to determine if a solution is acidic or basic. Litmus paper, made from lichens by treating paper with natural dyes, serves as a type of pH paper. Blue litmus paper turns red or pink when it contacts an acidic solution with a pH below 4.5. It becomes purple if the solution's pH is between 4.5 and 8.3, and it stays blue if the pH is above 8.3.