What causes the green solution when an iron nail is placed in copper sulphate solution?
Answer and explanation
Correct answer: Formation of iron sulphate
Iron is above copper in the reactivity series, so it can displace copper from copper sulphate solution. The reaction is Fe + CuSO₄ → FeSO₄ + Cu. Aqueous iron(II) sulphate is pale green, while copper metal deposits on the nail. Therefore formation of iron sulphate explains the green colour. The other proposed compounds contain elements not involved in this reaction, so A is correct.
Frequently asked questions
What is the correct answer to this question?
Formation of iron sulphate
Why is this the correct answer?
Iron is above copper in the reactivity series, so it can displace copper from copper sulphate solution. The reaction is Fe + CuSO₄ → FeSO₄ + Cu. Aqueous iron(II) sulphate is pale green, while copper metal deposits on the nail. Therefore formation of iron sulphate explains the green colour. The other proposed compounds contain elements not involved in this reaction, so A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
