Which two elements are removed from water by the softener through ion exchange?

The process of ion exchange in a water softener primarily targets the removal of hardness-causing minerals, specifically calcium and magnesium ions. These two elements are common contributors to water hardness, which can lead to scaling in pipes and appliances, reduced soap efficiency, and other issues associated with hard water.

In the ion exchange process, the hard water passes through a resin bed that is preloaded with sodium ions. As the hard water flows through, the calcium and magnesium ions in the water are exchanged for sodium ions. This effectively reduces the hardness of the water, making it softer and more suitable for household uses such as cleaning and bathing.

The other options listed do not pertain to the primary function of a water softener. Sodium and potassium, for instance, are not typically removed but rather exchanged during the softening process. Chlorine and nitrogen are generally handled by other water treatment processes, such as filtration or disinfection, rather than ion exchange. Similarly, sulfates and phosphates may require specific treatment methods, but they are not the focus of conventional softening operations.