Science (086) — AI-generated practice question

This is a displacement reaction.

The chemical equation is:

$$\text{Fe}(s) + \text{CuSO}_4(aq) \rightarrow \text{FeSO}_4(aq) + \text{Cu}(s)$$

Iron displaces copper from copper sulphate solution because iron is more reactive than copper. The Cu²⁺ ions responsible for the blue colour of copper sulphate are replaced by Fe²⁺ ions (forming colourless iron sulphate), so the blue colour fades. The displaced copper deposits on the nail as a brownish coating.

Source: Chapter 1, Section 1.2.3 – Displacement Reaction

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• 1 mark for naming the reaction type (displacement reaction).
• 1 mark for the balanced chemical equation.
• 1 mark for explaining why the blue colour fades — examiners want you to link the loss of Cu²⁺ ions to the formation of FeSO₄ (which is pale/colourless in dilute solution), not just say "iron takes the place of copper."
• Always write the equation with state symbols — it shows precision and is expected at board level.