Question

The presence of soluble fluoride ion upto 1 ppm concentration in drinking water, is :

• A. safe for teeth
• B. harmful to bones
• C. harmful for teeth
• D. harmful to skin

Answer 1

The correct option is A safe for teeth

Soluble fluoride is often added to drinking water to make concentration upto 1 ppm because $F^{-}$ions make the enamel on teeth much harder. But above 2 ppm cause brown mottling of teeth and hence caus ing harmful effect on bones and teeth.