Which sodium compound is utilized to eliminate oxygen from boiler water?

The correct choice is sulfite, which is used to eliminate oxygen from boiler water. In boiler water treatment, the presence of oxygen can lead to corrosion, which can damage the boiler and reduce its efficiency. Sulfite compounds, such as sodium sulfite, serve as effective oxygen scavengers. When added to boiler water, sulfite reacts with oxygen to form sulfate, thus removing oxygen from the water and protecting the boiler from corrosion.

Sulfite is particularly valuable because it not only removes dissolved oxygen but also typically stays in solution, allowing for continuous protection. This function is vital for maintaining the longevity and operational efficiency of boilers in various industrial applications, making sulfite an essential component of boiler water treatment practices.

Other compounds, like sulfate, phosphate, and nitrate, don’t serve the purpose of oxygen elimination in the same way. While they may have other roles in water treatment—such as preventing scale formation or serving as nutrients—they do not effectively scavenge oxygen and, therefore, do not fulfill the requirement specified in the question.