Science of Litmus Paper

To test substances, we use litmus paper, a natural indicator made from lichens. Blue litmus paper

turns red if the substance is acidic. Let's test some samples like lemon juice and vinegar.

Now let's test the same samples on red litmus paper. If the substance is basic,

red litmus turns blue. Try it with soap solution, lime water,

and baking soda. Substances turning blue litmus red go in group A. They are acidic.

Red litmus to blue? Group B, basic. No color change? That's group C,

neutral. Let's sort them now. But what exactly is litmus?

It's a natural dye from lichens, tiny organisms found on rocks and trees. Litmus helps us