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Q.
Hardness of water is $200$ ppm. The normality of $CaCO_{3}$ in the water is in the form of $y\times 10^{3}$. Identify $y$.
Hydrogen
Solution:
Hardness is weight in grams of $CaCO_{3}$ in $10^{6}$ mL of $H_{2}O$
$(\because d\,$ of $\,H_{2}O = 1)$
or Hardness $= 10^{6} g$ of $H_{2}O$
$MW\left(CaCO_{3}\right) = 100g$ mol $^{-1}$
$M = \frac{W_{2} \times1000}{MW \times \text{Vol. of solution in mL}}$
$= \frac{200 \times1000}{100 \times10^{6}} = 2 \times10^{-3}M$
$N = v. f \times M $
$=2 \times2 \times10^{-3} $
$=4 \times10^{-3}N$