Question

A water sample has ppm level concentration of following anions, $F^{-}=10,S{O}_4^{2-}=100,N{O}_3^{-}=50$. The anion/anions that make/makes the water sample unsuitable for drinking is/are :

• A. Only $S{O}_4^{2-}$
• B. Only $F^{-}$
• C. Both $S{O}_4^{2-}\text{and}N{O}_3^{-}$
• D. Only $N{O}_3^{-}$

Answer 1

The correct option is B Only $F^{-}$

Above $500\text{ppm}$ of $S{O}_4^{2-}$ ions in drinking water, can cause laxative effect otherwise lesser $\text{ppm}$ value is permissible for drinking maximum limit of $N{O}_3^{-}$ ions in drinking water is
$50\text{ppm}$, above this limit it can cause the disease like methemoglobinemia. More than $1\text{ppm}$ $F^{-}$ ions in drinking water are not fit for drinking, it can cause decay of bones and teeth.