Question

A dental disease characterized by mottling of teeth is due to the presence of certain chemical element in drinking water. Which of the following is that element?

• A. fluorine
• B. boron
• C. mercury
• D. chlorine.

Answer 1

The Correct Option is A

The question asks about a dental disease characterized by mottling of teeth due to a chemical element in drinking water. Let's break this down:

1. Understanding the term "mottling of teeth": Mottling of teeth, also known as dental fluorosis, occurs when there is an excessive intake of fluoride over a period of time while the teeth are developing.
2. Identification of the chemical element:
   • Fluorine (\text{F}) is the chemical element responsible for fluorosis when present in high amounts in drinking water. It leads to changes in tooth enamel, which can cause discoloration or "mottling."
   • The other options, boron, mercury, and chlorine, do not cause this specific dental effect. Boron is used in various industrial applications, mercury is a toxic element with different health effects, and chlorine is used in water purification.
3. Conclusion: The presence of fluorine in drinking water is responsible for the dental disease characterized by mottling of teeth.

Therefore, the correct answer is {\text{fluorine}}.