Question:
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 $\left[3 \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2} \cdot \mathrm{Ca}(\mathrm{OH})_{2}\right]$ to :
Correct Option: , 2
Solution: