Question

A water sample has $\mathrm{ppm}$ level concentration of following anions

${\mathrm{F}}^{-}=10;{\mathrm{SO}}_4^{2-}=100;{\mathrm{NO}}_3^{-}=50$

The anion/ anions that makes the water sample unsuitable for drinking is/are:

• A. Only ${\mathrm{F}}^{-}$
• B. Only ${\mathrm{SO}}_4^{2-}$
• C. Only ${\mathrm{NO}}_3^{-}$
• D. Only ${\mathrm{SO}}_4^{2-}\mathrm{and}{\mathrm{NO}}_3^{-}$

Answer 1

The correct option is A

Only ${\mathrm{F}}^{-}$

Answer(A)

Explanation for correct option:

The permissible limit of ${\mathrm{F}}^{-}$ in drinking water is up to $0.5-1\mathrm{ppm}$.

Excess concentration of ${\mathrm{F}}^{-}>10\mathrm{ppm}$ causes decay of bones.

Explanation of incorrect option:

(B) The maximum permissible limit of ${{\mathrm{SO}}_4}^{-2}$ in water is $250\mathrm{ppm}$. Hence the given concentration is sufficient for drinking water. Therefore, option (B) is incorrect

(C) The maximum permissible limit of ${{\mathrm{NO}}_3}^{-}$ in water is $50\mathrm{ppm}$. Hence the given concentration is sufficient for drinking water. Therefore, option (C) is incorrect

(D) When (B) and (C) options are wrong, automatically option (D) is incorrect.

Hence option (A) correct option.