JEE PYQ: Hydrogen Question 31
Question 31 - 2019 (12 Jan Shift 2)
The hardness of a water sample (in terms of equivalents of $\text{CaCO}_3$) containing $10^{-3}$ M $\text{CaSO}_4$ is: (molar mass of $\text{CaSO}_4$ = 136 g mol$^{-1}$)
(a) 10 ppm (b) 50 ppm (c) 90 ppm (d) 100 ppm
Show Answer
Answer: (d)
Solution
$10^{-3}$ M $\text{CaSO}_4 \equiv 10^{-3}$ M $\text{CaCO}_3$. $W = 10^{-3} \times 100 = 100$ mg per litre = 100 ppm.