A student placed an iron nail in blue copper sulphate solution. The solution gradually turned green and a reddish-brown coating appeared on the nail. Which statement is correct?
Answer and explanation
Correct answer: It is a displacement reaction in which iron displaces copper from its salt.
Iron is above copper in the reactivity series, so it displaces copper from copper sulphate: Fe + CuSO₄ → FeSO₄ + Cu. The newly formed iron sulphate solution is pale green, while copper appears as the reddish-brown coating on the nail. Thus A correctly explains both observations. The reaction is not combination, decomposition by heating, or neutralisation because no acid-base reaction is involved.
Frequently asked questions
What is the correct answer to this question?
It is a displacement reaction in which iron displaces copper from its salt.
Why is this the correct answer?
Iron is above copper in the reactivity series, so it displaces copper from copper sulphate: Fe + CuSO₄ → FeSO₄ + Cu. The newly formed iron sulphate solution is pale green, while copper appears as the reddish-brown coating on the nail. Thus A correctly explains both observations. The reaction is not combination, decomposition by heating, or neutralisation because no acid-base reaction is involved.
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.
