Which elements are classified as halogens in water treatment?

Halogens are a group of elements that are known for their reactivity and tendency to form salts with metals. In the context of water treatment, chlorine, bromine, and iodine are particularly important because they are commonly utilized for disinfection and purification.

Chlorine is widely used in water treatment facilities as a disinfectant to kill harmful microorganisms, ensuring that the water is safe for consumption. Bromine can also be used in some applications, especially in hot tubs and swimming pools, due to its effectiveness in warmer water. Iodine, while less commonly used on a large scale than chlorine, has antiseptic properties and can be used for water purification in smaller-scale applications, such as in survival or camping situations.

The other choices list elements that do not belong to the halogen group. Carbon, nitrogen, and oxygen are essential elements for life but are not classified as halogens. Similarly, hydrogen, helium, and lithium are classified as nonmetals and noble gases, respectively, and do not share the properties that define halogens. Sodium, potassium, and calcium are alkali and alkaline earth metals and do not fit into the halogen classification.

Understanding the role of chlorine, bromine, and iodine in water treatment is crucial for effective