Question:
The hardness of a water sample (in terms of equivalents of $\left.\mathrm{CaCO}_{3}\right)$ containing $10^{-3} \mathrm{M} \mathrm{CaSO}_{4}$ is:
$\left(\right.$ molar mass of $\left.\mathrm{CaSO}_{4}=136 \mathrm{~g} \mathrm{~mol}^{-1}\right)$
Correct Option: 1
Solution:
ppm of $\mathrm{CaCO}_{3}$
$\left(10^{-3} \times 10^{3}\right) \times 100=100 \mathrm{ppm}$