Softening of hard water is done by:

A. Aeration
B. Boiling
C. Lime soda
D. Ozonation
E. Ion exchange

Choose the correct answer from the options given below:

Correct option is B

Hard water softening involves removing calcium (Ca2+) and magnesium (Mg2+) ions, which are responsible for water hardness. Methods include:
1. Boiling (B):
· Temporary hard water (caused by bicarbonates) can be softened by boiling, as it converts soluble bicarbonates to insoluble carbonates, which precipitate out.
2. Lime Soda Process (C):
· Adding lime (Ca(OH)2) and soda ash (Na2CO3​) removes hardness by precipitating calcium and magnesium as their respective carbonates and hydroxides.
3. Ion Exchange (E):
· Hard water passes through a resin that exchanges sodium ions (Na+) for calcium and magnesium ions, effectively softening the water.
Information Booster:
1. Types of Water Hardness:
· Temporary Hardness: Caused by bicarbonates, removable by boiling.
· Permanent Hardness: Caused by sulfates and chlorides, removable by chemical treatments or ion exchange.
2. Methods for Water Softening:
· Boiling: Simple but effective for temporary hardness.
· Lime Soda: Cost-effective for large-scale operations.
· Ion Exchange: Produces very soft water, suitable for industrial and domestic use.
3. Disadvantages of Hard Water:
· Scaling in pipes and appliances.
· Reduced efficiency of soaps and detergents.
· Harmful for industrial processes.
Additional knowledge:
1. Aeration (A):
· Aeration removes dissolved gases (like CO2​) and oxidizes some iron or manganese, but it does not soften water.
2. Ozonation (D):
· Ozonation is used for disinfection and oxidation, not for removing hardness-causing ions.