Which of the following substances cause temporary hardness in water? 1. Mg(HCO3)2 2. Ca(HCO3)2 3. CaCl2 4. MgSO4 Select the correct answer using the code given below:

CDS 2018 PYQ with Answer — Which of the following substances cause temporary hardness in water?…

2018 · Q30

Which of the following substances cause temporary hardness in water?

1Mg(HCO3)2
2Ca(HCO3)2
3CaCl2
4MgSO4

Select the correct answer using the code given below:

General KnowledgeChemistry

A3 and 4
B2 and 3
C1 and 4
D1 and 2

Explanation

Temporary hardness is caused by the bicarbonates of calcium and magnesium — Ca(HCO3)2 and Mg(HCO3)2 — and can be removed by boiling. The chlorides and sulphates of calcium and magnesium (CaCl2, MgSO4) cause permanent hardness instead. Hence the answer is 1 and 2.