Question

is a halogen used in gaseous and liquid form for large - scale disinfection of drinking water and sewage.multiple choicechlorineiodinefluorinebromineall of the choices are correct.

Explanation:

Chlorine is commonly used in gaseous (as \(Cl_2\)) and liquid (as sodium hypochlorite solution which contains \(ClO^-\)) forms for disinfecting drinking water and sewage. Iodine is used in smaller - scale applications like in some medical antiseptics. Fluorine is highly reactive and not used in this context for water disinfection. Bromine is used in some specialized water treatment but not as widely as chlorine for large - scale drinking water and sewage disinfection.

Answer:

Chlorine