Permanent hardness is caused by the dissolved __(sulphates/bicarbonates) of calcium and magnesium.

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Solution

The hardness of some water samples can be removed by boiling but not of all. On this basis, hard water is classified into two types.

When the hardness of a water sample can be removed by boiling, it is called temporarily hard water.

When the hardness of a water sample cannot be removed by boiling, it is called permanently hard water.

Temporary hardness is caused by the dissolved bicarbonates of calcium and magnesium.Permanent hardness is caused by the dissolved sulphates and chlorides of calcium and magnesium.

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Similar questions

Q. Permanent hardness is due to the presence of soluble salts of magnesium and calcium in the form of chlorides and sulphates in water. Permanent hardness of water can be removed by:

Q. Assertion :Permanent hardness of water can be removed by using washing soda Reason: Washing soda reacts with soluble calcium and magnesium chlorides and sulphates in hard water to form insoluble carbonates

Q. Consider the following statements:
Hard water does not give lather with soap because hard water contains:
(a) calcium bicarbonate
(b) magnesium bicarbonate
(c) chlorides of calcium and magnesium
(d) sulphates of calcium and magnesium
Which of these statements are correct?

Q. Assertion (A): Permanent hardness of water is removed by treatment with washing soda.
Reason(R): Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble compounds.

Assertion (A): Permanent hardness of water is removed by treatment with washing soda.
Reason(R): Washing soda reacts with soluble magnesium and calcium sulphate to form water-soluble compounds.

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