Which of the following statements are true about hardness in water? Choose the correct answer from the options given below.

1.It is caused by ions of calcium and magnesium

2.It is of two types, temporary and permanent

3.Permanent hardness can easily be removed by heating the water

4.Hardness causes scales in hot water pipe systems

5.Hardness decreases the soap consumption

A1, 2, 3 and 4 only

B1, 2 and 4 only ✓ Correct

C2, 3, 4 and 5 only

D3, 4 and 5 only

Correct answer: (B) 1, 2 and 4 only

Explanation

Water hardness comes from dissolved calcium and magnesium ions, mainly as bicarbonates, sulphates and chlorides.

Statement 1 is right: calcium and magnesium ions are indeed the cause of hardness.

Statement 2 is right: hardness is classed as temporary carbonate and permanent non-carbonate types.

Statement 3 is wrong: only temporary hardness leaves on boiling, while permanent hardness needs chemical softening.

Statement 4 is right: hardness deposits scale inside boilers and hot-water pipes.

Statement 5 is wrong: hard water raises, not lowers, soap consumption because it forms scum.

Permanent hardness is commonly removed by the lime-soda or ion-exchange method.

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