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Railways R.R.C. (Ahmedabad) Solved Paper Held on 1st Shift 9-11-2014

  • question_answer
    Permanent hardness of water can be removed by adding-

    A) Chlorine

    B) Washing soda

    C) Potassium permanganate

    D) Bleaching powder

    Correct Answer: B

    Solution :

    Washing soda also known as sodium carbonate (\[N{{A}_{2}}C{{O}_{3}}\]) can remove permanent hardness of water. Calcium and magnesium ions present in hard water react with sodium carbonate to produce insoluble carbonates. The water now contains soluble and harmless sodium salts.


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