Question

A water sample has ppm level concentration of following anions $F^{-} = 10 ;\, SO^{2-}_4 = 100 ;\, NO^{-}_3 = 50$ The anion/anions that make/makes the water sample unsuitable for drinking is / are :

• A. only $F^{-}$
• B. only $SO_4^{2-}$
• C. only $NO_4^{2-}$
• D. only $SO_4^{2-}$ and $NO^{-}_3$

Answer 1

Answer: (A)

only $F^{-}$

Answer 2

Permissible limit of $F ^{-}$ in drinking water is upto 1 ppm. Excess concentration of $F ^{-}>10\, ppm$ causes decay of bones.