Permanent hardness of water can easily be softened by adding which of the following chemicals?

Options :
  1. Potassium Permanganate
  2. Chlorine
  3. Bleaching Powder
  4. Washing Soda
Answer and Explanation :-

Answer: Option 4


Hard water is basically water that contains a significant quantity of dissolved minerals, such as Calcium and Magnesium. Hard water is not harmful for human health but can pose serious problems in industrial settings by causing breakdown in boilers or cooling towers. There are two types of hardness: temporary hardness and permanent hardness. Temporary hardness can be removed by boiling the water, while Permanent hardness cannot be removed by boiling. Washing Soda or Sodium Carbonate (Na2Co3) is a sodium salt of carbonic acid that can soften both Temporary and Permanent hardness. It is soluble in water and adds a large amount of carbonate ions to the water. These react with dissolved calcium and magnesium ions, forming a precipitate of calcium or magnesium carbonate.

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