JEE Main Solved Paper 2017 Question 27
Question: A water sample has ppm level concentration of following anions $ {F^{-}}=10;,SO_4^{2-}=100;,NO_3^{-}=50 $ the anion/anions that make / makes the water sample unsuitable for drinking is / are : [JEE Main Solved Paper-2017]
Options:
A) only $ NO_3^{-} $
B) both $ SO_4^{2-} $ and $ NO_3^{-} $
C) only $ F- $
D) only $ SO_4^{2-} $
Show Answer
Answer:
Correct Answer: C
Solution:
- $ NO_3^{-}: $ The maximum limit of nitrate in drinking water is 50 ppm. Excess nitrate in drinking water can cause disease. Such as methemoglobinemia. $ SO_4^{2-}: $ above 500 ppm of $ SO _4^{2-} $ ion in drinking water causes laxative effect otherwise at moderate levels it is harmless $ {F^{-}}: $ Above 2ppm concentration of $ {F^{-}} $ in drinking water cause brown mottling of teeth.
$ \therefore $ The concentration given in question of $ SO_4^{2-} $ $ \And ,NO _3^{-} $ in water is suitable for drinking but the concentration of $ {F^{-}} $ (i.e 10 ppm) make water unsuitable for drinking purpose:
