Question

what is hardness write its unit also​

Answer 1

Answer:

So one way to measure hardness is in mol/L or mmol/L. Other common units are milligrams per liter (mg/L), grains per gallon (gpg) or parts per million (ppm). Parts per million just means how many ions of calcium or magnesium you have in a million molecules of water.

Answer 2

Answer:

Hard water is water that has high mineral content. Hard water is formed when water percolates through deposits of limestone, chalk or gypsum which are largely made up of calcium and magnesium carbonates, bicarbonates and sulfates.

Unfortunately it has many units and is converted from one to other to make calculations.

Most commonly used units include grains per gallon (gpg), parts per million (ppm), and milligrams per liter (mg/L).