JEE PYQ: Hydrogen Question 18
Question 18 - 2020 (09 Jan Shift 1)
The hardness of a water sample containing $10^{-3}$ M $\text{MgSO}_4$ expressed as $\text{CaCO}_3$ equivalents (in ppm) is ______. (molar mass of $\text{MgSO}_4$ is 120.37 g/mol)
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Answer: 100
Solution
$10^{-3}$ M $\text{MgSO}_4 \equiv 10^{-3}$ M $\text{CaCO}_3$. $W = 10^{-3} \times 100 = 0.1$ g = 100 mg per litre = 100 ppm.