Exams › JEE Advanced › Chemistry

Which of the following statements about fluoride ion concentration in drinking water are correct?

1. The recommended concentration of fluoride ion in drinking water is 1 ppm.
2. A fluoride concentration below 1 ppm leads to tooth decay (dental caries).
3. A fluoride concentration above 1 ppm causes brown mottling (discolouration) of teeth.
4. None of the above statements is correct.

Correct answer: The recommended concentration of fluoride ion in drinking water is 1 ppm.

Solution

The optimum fluoride level for dental health is 1 ppm. Below this level dental caries develops; above this level fluorosis (brown mottling) occurs. All three positive statements are individually correct facts from NCERT Chemistry.

Related JEE Advanced Chemistry questions

• Which of the following substances is classified as an antipyretic drug (a fever-reducing agent)?
• Match the following drugs with their correct classification: Paracetamol --- Antipyretic Seldane (terfenadine) --- Antihistamine Aspartame --- Artificial sweetening agent Which of the following statements about the above matching is true?
• Which of the following correctly describes the key structural feature of penicillin that is responsible for its antibiotic activity?
• Which of the following ions, when dissolved in water, reduces the lathering ability of soap?
• Which among the following is classified as an antibiotic?
• A patient is suffering from a deficiency of noradrenaline (norepinephrine). Which class of drug should be prescribed?

⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →