Here's why:
* Chlorine is a strong oxidizing agent. This means it readily accepts electrons from other substances.
* Litmus paper contains dyes. These dyes are organic compounds with complex structures.
* Chlorine reacts with the dyes in litmus paper. The chlorine oxidizes (removes electrons from) the dyes, changing their chemical structure. This change in structure alters the color of the dyes, causing the red litmus paper to turn white.
Essentially, chlorine "bleaches" the color out of the litmus paper by breaking down the dye molecules.
