How does washing soda help soften hard water?
Answer and explanation
Correct answer: By removing calcium and magnesium ions
Hard water contains dissolved calcium and magnesium ions, which react with soap to form scum and reduce lather. Washing soda supplies carbonate ions that precipitate these ions as insoluble carbonates, such as calcium carbonate. Removing the ions reduces hardness, so option A is correct. It does not soften water by forming hydrogen or chlorine gas, and making water acidic would not be the governing process.
Frequently asked questions
What is the correct answer to this question?
By removing calcium and magnesium ions
Why is this the correct answer?
Hard water contains dissolved calcium and magnesium ions, which react with soap to form scum and reduce lather. Washing soda supplies carbonate ions that precipitate these ions as insoluble carbonates, such as calcium carbonate. Removing the ions reduces hardness, so option A is correct. It does not soften water by forming hydrogen or chlorine gas, and making water acidic would not be the governing process.
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.
