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Computers and Chemistry General Knowledge Quiz
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Permanent hardness of water can be removed by adding
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A
washing soda
💡 Explanation:
Permanent hardness of water is caused by dissolved chlorides and sulfates of calcium and magnesium, which cannot be removed by boiling. Washing soda (sodium carbonate decahydrate, Na2CO3·10H2O) removes permanent hardness through a chemical reaction: sodium carbonate reacts with calcium and magnesium salts to form insoluble carbonates that precipitate out, softening the water. Potassium permanganate, chlorine, and bleaching powder are disinfectants/oxidizers, not water softeners.