2026 · Q27
Consider the following statements:
- 1The temporary hardness in water is due to the presence of bicarbonates of calcium.
- 2The permanent hardness in water is due to the presence of soluble chlorides and sulphates of calcium and magnesium.
- 3The permanent hardness in water is removed by adding Na2CO3 to water.
Which of the statements given above are correct?
General KnowledgeChemistry
- A1 and 2 only
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3
Explanation
Temporary hardness of water is caused by bicarbonates of calcium and magnesium (statement 1 true). Permanent hardness is caused by soluble chlorides and sulphates of calcium and magnesium (statement 2 true). Adding washing soda (Na2CO3) precipitates calcium and magnesium as insoluble carbonates, removing permanent hardness (statement 3 true). All three statements are correct.