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phuongninhhoang712k1
2 năm trước
Để răng chắc khỏe và giảm bệnh sâu răng thì hàm lượng flo trong nước cần đạt là 1,0-1,5mg/l . Hãy tính lượng natri florua cần phải pha vào trong nước có sẵn hàm lượng flo từ 0,5mg/l thành nước có hàm lượng flo đạt 1,2mg/l để cung cấp cho 40 triệu dân , mỗi người dùng 250lít nước/ngày. Giả sử natri florua không bị thất thoát trong các quá trình pha trộn và cung cấp đến nơi tiêu dùng.
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