Which salt is used to remove the permanent hardness of hard water?
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Answer and explanation
Correct answer: Sodium carbonate
Sodium carbonate, or washing soda
\(\mathrm{Na_2CO_3\cdot10H_2O}\), precipitates calcium and magnesium ions present in water as insoluble carbonates. Therefore, it is used to remove permanent hardness. Sodium hydrogen carbonate is not effective for this purpose.
Frequently asked questions
What is the correct answer to this question?
Sodium carbonate
Why is this the correct answer?
Sodium carbonate, or washing soda
\(\mathrm{Na_2CO_3\cdot10H_2O}\), precipitates calcium and magnesium ions present in water as insoluble carbonates. Therefore, it is used to remove permanent hardness. Sodium hydrogen carbonate is not effective for this purpose.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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