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 method is used for the estimation of the chlorine demand of water ? \nSelect and explain. \nA. Chloromcter, B. Horrock's apparatus, C. Berkfeld filter, D. Double pot method", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Horrock's apparatus o Chlorine demand of water can be estimated by Horrock's apparatus. o Chlorine demand of water is the amount of chlorine that is needed to destroy bacteria, and to oxidize all the organic matter and ammoniacal substances present in water. o It is the difference between the amount of chlorine added to the water, and the amount of residual chlorine remaining at the end of a specific period of contact (usually I hr), at a given temperature and pH of water.", 'role': 'assistant'}]