This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and Health, Subject name: Social & Preventive Medicine
Maximum permissible chloride level is 
Select and explain. 
A. 200 mg/litre, B. 300 mg/litre, C. 500 mg/litre, D. 600 mg/litre
D: 600 mg/litre
Answer: D: 600 mg/litre 
Explanation: (600mg/litre) (579- Park 19"') (629-Park 20th)* Any excess over the normal range should arouse suspicion of water contamination* The standard prescribed for chloride is 200 mg/litre *** The maximum permissible level is 600 mg/litre*** A single tablet of chlorine 0.5gm is sufficient to disinfect 20 litre of water** The principle in chlorination is to ensure a "Free" residual chlorine of 0, 5 mg/litre at the end of one hour contact**