2025 · Q35
Which one among the following determines the Hardness Index of fresh water?
General ScienceChemistry
- ATotal concentration of the Ca^2+ and Mg^2 ions in the fresh water
- BDifference of the pH value of the fresh water with respect to sulphuric acid
- CThe pH value of fresh water measured at room temperature and at one atmospheric pressure
- DThe molar ratio of D2O to H2O in fresh water
Explanation
The hardness index of fresh water is determined by the total concentration of calcium (Ca2+) and magnesium (Mg2+) ions, which form scale and interfere with soap. pH measurements and the D2O/H2O ratio have nothing to do with hardness.