This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment, Subject name: Social & Preventive Medicine
[{'content': 'In chlorination of water, the main disinfecting action is due to:- \nSelect and explain. \nA. Hydrogen ions, B. Hydrochloric acid, C. Hypochlorous acid, D. Chloride ions', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Chlorination of water: - Used for large scale purification of water & for drinking water. Disinfection action of chlorine in water is due to: Hypochlorous acid - major role in disinfection (HOCl). Hypochlorite ions - minor role in disinfection. Chloride has residual germicidal effect. It kills bacteria, many viruses but not spores . It oxidizes iron, manganese & hydrogen sulphide. It also destroys taste & odorproducing components. Chlorine acts best as a disinfection for water at: pH around 7.0', 'role': 'assistant'}]