Which of the following is not a water softener?

Options

A. `Na_(2)CO_(3)`
B. `Na_(2)SO_(4)`
C. Calgon
D. Permutit

Answer

B

Explanation

`rarr" "Na_(2)CO_(3)` precipitates out `Ca^(++)` and `Mg^(++)` from hard water as insoluble carbonates
`rarr" "` Calgon, `(NaPO_(3))_(6)`, exchanges `Ca^(++)` and `Mg^(++)` from hard water
`rarr" "` Permutit : common type of zeolite, it exchanges `Ca^(++)` and `Mg^(++)` from hard water with its `Na^(+)` and also not allow to pass large sized molecules from it.