Chlorine is commonly used for which of the following tasks in water treatment?

Chlorine is primarily used in water treatment for disinfection, making it effective in killing or inactivating harmful microorganisms such as bacteria, viruses, and protozoa present in the water supply. By adding chlorine to water, it helps ensure that the water is safe for drinking and effectively reduces the risk of waterborne diseases.

Disinfection is critical in the treatment process, as it provides a barrier against pathogens that may not be removed by other conventional methods like sedimentation or filtration. Chlorine is favored for its effectiveness, availability, and cost-efficiency in maintaining a safe water supply.

In contrast, flocculation involves the aggregation of particles to form larger flocs that can be more easily removed from water, which relies on different chemical coagulants rather than chlorine. Filtration is a physical process that removes particles from water, also not relying on chlorine. Neutralization, on the other hand, refers to adjusting the pH levels of water and typically makes use of acids or bases, not chlorine. Thus, the primary role of chlorine in the context of water treatment is indeed disinfection.