Washing soda softens hard water by removing which ions?
Answer and explanation
Correct answer: Calcium and magnesium ions
Hardness of water is mainly caused by dissolved calcium and magnesium ions. Washing soda, sodium carbonate decahydrate, supplies carbonate ions that react with them to form insoluble calcium carbonate and magnesium carbonate. These precipitates can be removed, reducing hardness. Sodium and chloride ions do not cause ordinary hardness, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
Calcium and magnesium ions
Why is this the correct answer?
Hardness of water is mainly caused by dissolved calcium and magnesium ions. Washing soda, sodium carbonate decahydrate, supplies carbonate ions that react with them to form insoluble calcium carbonate and magnesium carbonate. These precipitates can be removed, reducing hardness. Sodium and chloride ions do not cause ordinary hardness, so option A is correct.
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.
