Hardness of water is expressed in terms of:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. ppm.
The hardness of water is typically expressed in terms of the concentration of calcium carbonate (CaCO₃) equivalents. It is measured in milligrams per liter (mg/L) or parts per million (ppm). This standard unit allows for the comparison of the hardness of water from different sources, regardless of the specific minerals causing the hardness.