How does washing soda help in softening hard water?
Answer and explanation
Correct answer: It removes calcium and magnesium ions as insoluble carbonates
Hard water contains dissolved calcium and magnesium ions, which react with soap to form scum and prevent good lather. Washing soda, sodium carbonate (Na₂CO₃), supplies carbonate ions. These combine with calcium and magnesium ions to form insoluble carbonates that can precipitate and be removed. Thus A is correct; washing soda does not acidify water, convert it into gas, or generate chlorine.
Frequently asked questions
What is the correct answer to this question?
It removes calcium and magnesium ions as insoluble carbonates
Why is this the correct answer?
Hard water contains dissolved calcium and magnesium ions, which react with soap to form scum and prevent good lather. Washing soda, sodium carbonate (Na₂CO₃), supplies carbonate ions. These combine with calcium and magnesium ions to form insoluble carbonates that can precipitate and be removed. Thus A is correct; washing soda does not acidify water, convert it into gas, or generate chlorine.
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.
