Question

acid change the colour for litmus paper

Answer 1

Blue litmus paper turns red under acidicconditions and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple.

Answer 2

Blue litmus turns red when an acid is dropped on the litmus paper. But it does not changes the red litmus paper.