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NDA 2 2025 GAT, question 106

Topic: Chemistry

Q106

Which one of the following salts is responsible for temporary hardness of water ?

  1. (a) Sulphates of calcium
  2. (b) Chlorides of magnesium
  3. (c) Bicarbonates of magnesiumCorrect answer
  4. (d) Sulphates of magnesium

Solution.

Answer: (c) Bicarbonates of magnesium

  1. Temporary hardness comes from dissolved calcium or magnesium bicarbonates and can be removed by boiling.
  2. Sulphates and chlorides principally produce permanent hardness.
  3. Thus magnesium bicarbonate is the correct choice.