Water mein fluoride kyu add karte hain?

Aise kaun se metals hain jo Haath mein rakhte hi melt ho jaate hain?

The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be 1000 ppb,40 ppb,100 ppm and 0.2 ppm, respectively. This water is unsuitable for drinking due to high concentration of

The concentration of iron, lead ,nitrate, and fluoride in a water sample from an underground lake was found to be 0.18 ppm, 35 ppb, 80 ppm and 1000 ppb, respectively. This water is unsuitable for drinking due to high concentration of

Astronauts space mein kyun karte hai float

Kya aapko pata hai aise bhi Metals hain jo haath mein rakhte hi pighal jate hain!!