Hardness of water can be removed by the addition of which of the following compounds?

💡 Solution & Explanation

Washing soda or sodium carbonate removes both temporary and permanent hardness of water by reacting with dissolved calcium and magnesium salts to form insoluble precipitates that can be easily filtered out. Neutral salts like sodium chloride do not precipitate hardness ions and therefore cannot soften hard water. Water softening is essential for preventing scaling in industrial boilers and domestic plumbing systems.