JEE Main 2022 — Environmental Chemistry Question with Solution

${\mathrm{F}}^{-}$ ion concentration above $2 \mathrm{ppm}$ causes brown mottling of teeth. At the same time, excess fluoride (over $10 \mathrm{ppm}$) causes harmful effect to bones and teeth

Lead: Drinking water gets contaminated with lead when lead pipes are used for transportation of water. The prescribed upper limit concentration of lead in drinking water is about $50 \mathrm{ppb}$. Lead can damage kidney, liver, reproductive system etc.

Sulphate: Excessive sulphate $\left(>500 \mathrm{ppm}\right)$ in drinking water causes laxative effect, otherwise at moderate levels it is harmless.

Nitrate: The maximum limit of nitrate in drinking water is $50 \mathrm{ppm}$. Excess nitrate in drinking water can cause disease such as methaemoglobinaemia ('blue baby' syndrome).