Calcium bicarbonate (Ca(HCO3)₂) is a common salt found dissolved in water that causes temporary hardness. When heated, calcium bicarbonate decomposes to form calcium carbonate, which precipitates out, reducing the hardness. Calcium carbonate (CaCO₃) itself is largely insoluble in water under normal conditions and does not dissolve significantly to cause hardness.
Which one among the following salts causes hardness to the water?
Asked in UPSC CAPF 2012 · Topic: Physical and Chemical Changes, Solution (Solubility and Factors Affecting Solubility (Temperature, Pressure))
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Answer: A. Calcium bicarbonate
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