A water supply has very hard water with calcium ion (Ca2+) concentration of 200 mg/L. With such hard water, what is the highest concentration of dissolved fluoride (in mg/L) that could be provided in the finished water if no softening is performed? the Ksp for CaF2 is 3x10^-11. Note that the beneficial concentration of fluoride is about 1 ppm, and it can cause health problems above 4 ppm.