Which chemical formula represents washing soda, used for washing clothes and softening hard water?
Answer and explanation
Correct answer: Na₂CO₃·10H₂O
Washing soda is sodium carbonate decahydrate, whose chemical formula is Na₂CO₃·10H₂O. The dot and the coefficient 10 show that each formula unit contains ten molecules of water of crystallisation; “deca” means ten. NaHCO₃ is baking soda, CaOCl₂ is bleaching powder, and CaSO₄·½H₂O is Plaster of Paris. Therefore option B is correct.
Frequently asked questions
What is the correct answer to this question?
Na₂CO₃·10H₂O
Why is this the correct answer?
Washing soda is sodium carbonate decahydrate, whose chemical formula is Na₂CO₃·10H₂O. The dot and the coefficient 10 show that each formula unit contains ten molecules of water of crystallisation; “deca” means ten. NaHCO₃ is baking soda, CaOCl₂ is bleaching powder, and CaSO₄·½H₂O is Plaster of Paris. Therefore option B 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.
