JEE PYQ: P Block Elements Question 31
Question 31 - 2020 (06 Sep Shift 1)
The presence of soluble fluoride ion upto 1 ppm concentration in drinking water, is:
(1) harmful for teeth
(2) harmful to skin
(3) harmful to bones
(4) safe for teeth
Show Answer
Answer: (4)
Solution
Fluoride ($\text{F}^-$) ion conc. upto 1 ppm makes the enamel of teeth much harder by converting hydroxyapatite to fluorapatite. But above 2 ppm causes brown mottling of teeth.
BETA
