Washing soda crystals become powdery when kept in open air. Which phenomenon does this illustrate?
Answer and explanation
Correct answer: Efflorescence
Washing soda is sodium carbonate decahydrate, Na₂CO₃·10H₂O, so its crystals contain water of crystallisation. On exposure to comparatively dry air, some of this water is lost from the crystal lattice. The crystals become dull and powdery; this process is called efflorescence. Deliquescence involves absorbing moisture and dissolving, while neutralisation and displacement are chemical reaction types. Therefore B is correct.
Frequently asked questions
What is the correct answer to this question?
Efflorescence
Why is this the correct answer?
Washing soda is sodium carbonate decahydrate, Na₂CO₃·10H₂O, so its crystals contain water of crystallisation. On exposure to comparatively dry air, some of this water is lost from the crystal lattice. The crystals become dull and powdery; this process is called efflorescence. Deliquescence involves absorbing moisture and dissolving, while neutralisation and displacement are chemical reaction types. Therefore 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.
