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NDA 2025
Exam
NDA
Year
2025
Subject
General Ability
Chapter
General Science

NDA 2025 · General Ability · General Science

Which one of the following salts is responsible for temporary...

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

Options

  1. ASulphates of calcium
  2. BChlorides of magnesium
  3. CBicarbonates of magnesium
  4. DSulphates of magnesium

Correct answer

C. Bicarbonates of magnesium

Step-by-step solution

Temporary hardness of water is caused by the presence of dissolved bicarbonates of calcium and magnesium, namely Ca(HCO3)2Ca(HCO_3)_2 and Mg(HCO3)2Mg(HCO_3)_2.

Permanent hardness of water is caused by the presence of dissolved chlorides and sulphates of calcium and magnesium.

Therefore, bicarbonates of magnesium are responsible for the temporary hardness of water.

Answer: Bicarbonates of magnesium
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