Here's why:

* Disinfectants: Chlorine is widely used in disinfectants because it is a powerful oxidizing agent. It kills bacteria, viruses, and other microorganisms by disrupting their cell membranes and interfering with their metabolic processes.

* Chemical Weapons: Chlorine gas was used as a chemical weapon during World War I. It is highly toxic and can cause severe respiratory problems, leading to suffocation.

While other halogens like bromine and iodine also have antimicrobial properties, chlorine is the most commonly used in disinfectants and was historically used as a chemical weapon due to its availability and effectiveness.