Assertion : It is necessary to know the concentration of flouride ion in dirnking water. Reason: The increase in amount of fluride ion causes tribes in tooth and bones.

Assertion : It is necessary to know the concentration of flouride ion

1.	Assertion : It is necessary to know the concentration of flouride ion in dirnking water. Reason: The increase in amount of fluride ion causes tribes in tooth and bones.
Answer» Both Assertion and Reason are correct and the reason is the correct EXPLANATION for assertion. Both assertion and reason are correct, but the reason is not correct explanation of assertion. Both the assertion and reason are incorrect. The assertion is incorrect but the reason is correct. Solution :Amount of `F^-` ION is UPTO 1 ppm it make the enamel on teeth much harder by converting hydroxy APATITE into fluorapatite. Amount is above 2 ppm it causes brown mottling of teeth. Amount is above 10 ppm it causes harmful effect to bones and teeth.