The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to make teeth enamel harder by converting [3Ca(PO_4)2. Ca(OH)_2] to :

The recommended concentration of fluoride ion in drinking water is up

1.	The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to make teeth enamel harder by converting [3Ca(PO_4)2. Ca(OH)_2] to :
Answer» `[CaF_2]` `[3CaF_2^* CA(OH)_2]` `[3Ca_3 (PO_4)_2 * CaF_2]` `[3(Ca(OH)_2]* CaF_2]` Solution :F is NEEDED to make the teeth enamel harder . Which is POSSIBLE by converting `[3Ca_3 (PO_4)_2 . Ca(OH)_2]` into `[3Ca_3 (PO_4)_2 CaF_2]`