This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'Which one of the following methods is used for the estimation of chlorine demand of water? \nSelect and explain. \nA. Horrock’s apparatus, B. Chlorometer, C. Berkefeld filter, D. Double pot method', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Chlorine demand of water : Is the amount of chlorine that is needed to destroy bacteria, and to oxidize all the organic\xa0matter amd ammoniacal substances present in water.\n\nIs the amount of chlorine added to water minus amount of residual chlorine remaining at the end of a specific\xa0period of contact (1 hr).\nEstimation of chlorine demand of water (or dose of bleaching powder required for disinfection of water) is done\xa0by ‘Horrock’s apparatus.', 'role': 'assistant'}]