CAPF AC 2019 PYQ with Answer — Which one of the following is used for water softening?

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CAPF AC 2019 · Paper I: General Ability and IntelligenceQ55

Back to the full 2019 paper

2019 · Q55

Which one of the following is used for water softening?

general-sciencechemistry

AMg(HCO3)2
BNa3PO4
CNa6P6O18
DNa2HPO4

Explanation

Sodium hexametaphosphate, Na6P6O18 (Calgon), sequesters calcium and magnesium ions and is the standard water-softening agent. Mg(HCO3)2 causes temporary hardness rather than removing it, and the other phosphates listed are not the softening agent. The stored key A has been corrected per UPSC's official answer key.

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