Question:
The temporary hardness of water is due to the presence of
The temporary hardness of water is due to the presence of
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Remember: Bicarbonates cause Boiling-reversible (temporary) hardness. Chlorides and sulfates cause permanent hardness.
Updated On: Jun 3, 2026
- Calcium and Magnesium chlorides
- Calcium and Magnesium sulfates
- Calcium and Magnesium bicarbonates
- Sodium and Potassium carbonates
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The Correct Option is C
Solution and Explanation
Step 1: Concept
Hardness in water is caused by dissolved mineral salts of calcium and magnesium. It is classified into two types: temporary hardness and permanent hardness.
Step 2: Meaning
Temporary hardness can be easily removed by boiling, whereas permanent hardness requires chemical treatment.
Step 3: Analysis
Let us look at the salts responsible: * Permanent hardness is caused by soluble chloride and sulfate salts of calcium and magnesium ($\text{CaCl}_{2}, \text{MgSO}_{4}$, etc.). * Temporary hardness is caused specifically by dissolved bicarbonate salts: calcium bicarbonate [$\text{Ca(HCO}_{3})_{2}$] and magnesium bicarbonate [$\text{Mg(HCO}_{3})_{2}$]. Boiling decomposes these soluble bicarbonates into insoluble carbonates, removing them from the water.
Step 4: Conclusion
Therefore, the presence of calcium and magnesium bicarbonates is responsible for temporary hardness.
Final Answer: (C)
Hardness in water is caused by dissolved mineral salts of calcium and magnesium. It is classified into two types: temporary hardness and permanent hardness.
Step 2: Meaning
Temporary hardness can be easily removed by boiling, whereas permanent hardness requires chemical treatment.
Step 3: Analysis
Let us look at the salts responsible: * Permanent hardness is caused by soluble chloride and sulfate salts of calcium and magnesium ($\text{CaCl}_{2}, \text{MgSO}_{4}$, etc.). * Temporary hardness is caused specifically by dissolved bicarbonate salts: calcium bicarbonate [$\text{Ca(HCO}_{3})_{2}$] and magnesium bicarbonate [$\text{Mg(HCO}_{3})_{2}$]. Boiling decomposes these soluble bicarbonates into insoluble carbonates, removing them from the water.
Step 4: Conclusion
Therefore, the presence of calcium and magnesium bicarbonates is responsible for temporary hardness.
Final Answer: (C)
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