How many molecules of water of crystallisation are present in washing soda?
Answer and explanation
Correct answer: Ten
The governing concept is hydration of salts. Washing soda is sodium carbonate decahydrate, written as Na₂CO₃·10H₂O. The dot followed by 10H₂O shows that each formula unit of sodium carbonate is associated with ten water molecules of crystallisation. Therefore, option A is correct. Two, five, and half do not match the established formula of washing soda and refer to no correct hydration state here.
Frequently asked questions
What is the correct answer to this question?
Ten
Why is this the correct answer?
The governing concept is hydration of salts. Washing soda is sodium carbonate decahydrate, written as Na₂CO₃·10H₂O. The dot followed by 10H₂O shows that each formula unit of sodium carbonate is associated with ten water molecules of crystallisation. Therefore, option A is correct. Two, five, and half do not match the established formula of washing soda and refer to no correct hydration state here.
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.
