Correct Answer - Option 1 : 100 ppm
Concept:
The hardness of the water sample can be calculated in terms of ppm concentration of CaCO3
The hardness of water = ppm of CaCO3
Calculation:
Given, molarity = 10-3 M
i.e., 1000 mL of solution contains 10-3 mole of CaCO3
∴ The hardness of water = ppm of CaCO3
\( = \frac{{{{10}^{ - 3}} \times 1000}}{{1000}} \times {10^6}\)
= 100 ppm.