Passing the hard water sample through a chemical exchanges the ions with the ion of the same charge. Identify the chemical, the ion that replaces and the type of hardness being removed.

Options

A. Permutit, `Na^+` ion, permanent hardness
B. Sodium carbonate, `Ca^(+2)` ion, temporary hardness
C. Calcium hydroxide, `Mg^(+2)` ion, temporary hardness
D. Sodium chloride, `Na^+` ion, permanent hardness

Answer

A

Explanation

Passing the hard water sample through a chemical
called permutit exchanges the ions in the hard water with ions of some charge. The `Ca^(+2)` and `Mg^(+2)` ions in the hardwarer are replaced by `Na^+` ions of permutit, which removes the permanent hardness of water.
Hence, the correct option is (a).