Polyphosphates are used as water softening agents because they

Options

A. form soluble complexes with anionic speciews
B. precipitate anionic species
C. form soluble complexes with cationic species
D. precipitate cationic species.

Answer

C

Explanation

Polyphosphates are used as water softening agents because they remove impurities `(CaSO_(4) & MgSO_(4))` present in a hard water.
`2CaSO_(4)+Na_(2)[Na_(4)(PO_(3))_(6)]rarrNa_(2)[Ca_(2)(PO_(3))_(6)]+2Na_(2)SO_(4)`
`2MgSO_(4)+Na_(2)[Na_(4)(PO_(3))_(6)]rarrNa_(2)[Mg_(2)(PO_(3))_(6)]+2Na_(2)SO_(4)`