Question

Distinguish between (i) hard water and soft water (ii) temporary and permanent hardness.

Answer 1

soft water is a sample of ground water which freely lathers with soap solution meanwhile hard water is a sample of ground water which forms sticky scum with soap solution.

temporary hardness is caused by hydrogen carbonates of magnesium and calcium. permanent hardness is caused by sulphates and chlorides of calcium and magnesium.
temporary hardness can be removed by boiling it but permanent hardenss can be removed by treating the water with sodium carbonate.