JEE Main 2023 — Environmental Chemistry Question with Solution

	Species	Maximum allowed concentration in ppm in drinking water
A.	${\mathrm{F}}^{-}$	$2$
B.	${\mathrm{SO}}_4^{2-}$	$500$
C.	${\mathrm{NO}}_3^{-}$	$50$
D.	$\mathrm{Zn}$	$5$

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

Excessive sulphate (>500 ppm) in drinking water causes laxative effect, otherwise at moderate levels it is harmless.

The maximum limit of nitrate in drinking water is 50 ppm. Excess nitrate in drinking water can cause disease such as methemoglobinemia (‘blue baby’ syndrome).