Which chemical is commonly added to municipal water supplies to help prevent tooth decay?

• A. Sodium fluoride (NaF)
• B. Calcium chloride (CaCl_2)
• C. Potassium permanganate (KMnO_4)
• D. Magnesium sulfate (MgSO_4)

Answer: (A)

Verified step by step guidance

1. Understand the purpose of adding chemicals to municipal water supplies, which is often to improve public health by preventing diseases or deficiencies.
2. Recall that tooth decay is caused by the demineralization of tooth enamel due to acids produced by bacteria in the mouth.
3. Identify that fluoride ions help strengthen tooth enamel and make it more resistant to acid attacks, thereby preventing tooth decay.
4. Recognize that sodium fluoride (NaF) is a common source of fluoride ions used in water fluoridation programs.
5. Conclude that among the given options, sodium fluoride (NaF) is the chemical commonly added to municipal water supplies to help prevent tooth decay.