Why does adding washing soda to hard water help in washing?
Answer and explanation
Correct answer: It helps remove calcium and magnesium ions
Hard water contains dissolved calcium and magnesium ions, which react with soap to form insoluble scum and prevent good lather. Washing soda, Na₂CO₃·10H₂O, supplies carbonate ions that precipitate these ions as insoluble carbonates, thereby softening the water. Hence, option B is correct. It does not increase hardness, convert soap into an acid, or change liquid water into a gas. Better lather then makes washing more effective.
Frequently asked questions
What is the correct answer to this question?
It helps remove calcium and magnesium ions
Why is this the correct answer?
Hard water contains dissolved calcium and magnesium ions, which react with soap to form insoluble scum and prevent good lather. Washing soda, Na₂CO₃·10H₂O, supplies carbonate ions that precipitate these ions as insoluble carbonates, thereby softening the water. Hence, option B is correct. It does not increase hardness, convert soap into an acid, or change liquid water into a gas. Better lather then makes washing more effective.
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.
