Question

Fluorine chlorine is a powerful bleaching agent why

Answer 1

Hypochlorous acid is unstable, and it easily dissociates to form nascentoxygen. Nascent oxygen is a more powerful oxidising agent. Its formation is responsible for the bleaching nature of chlorine in the presence of moisture

Answer 2

Fluorine is such a powerful oxidizing agent that solution reactions are unfeasible. Chlorine has the ability to take electrons from both bromide ions and iodide ions.

This indicates that chlorine is a more powerful oxidizing agent than either bromine or iodine.