Water obtained by purification with organic ion exchange resins is

Options

A. Pure water
B. Free from only `Ca^(2+),Mg^(2+)` ions
C. Free from `HCO_(3)^(-),SO_(4)^(2-)` and `Cl^(-)` ions only
D. None of these

Answer

D

Explanation

Ion exchange resins remove all soluble minerals from water. The hard water is first passed through a bed of cation exchanger, which removes the cations like `Na^(+),Mg^(2+),Ca^(2+)` and others by exchanging with `H^(+)` ions.
`underset("Resin")2RH+Ca^(2+)rarr(R)_(2)Ca+2H^(+)`
The water coming from cation exchanger is acidic on account of free `H^(+)` ions. This water is then passed through another bed containing anion exchanger. This exchanger removes anions like `Cl^(-),SO_(4)^(2-),NO_(3)^(-)` by exchanging with `OH^(-)` ions.
`R-underset("Resin")NH_(3)OH+Cl^(-)rarrR-NH_(3)Cl+OH^(-)`