Paper 4 Metals Structured Practice
5 structured exam questions on metals for IGCSE Chemistry Paper 4. Covers reactivity series, displacement reactions, extraction of metals, rusting, and alloys. Total: 25 marks.
Published by IGCSEChemistry.com.my
Chemistry teaching team: K. S. Tan (15+ years teaching IGCSE Chemistry) and Ms Yash (10+ years teaching IGCSE Chemistry) and Ms Kartini (15+ years teaching IGCSE Chemistry).
Mapped to Cambridge IGCSE Chemistry 0620 (2026–2028). Last updated 2026-08-19.
Five structured questions in the style of IGCSE Chemistry Paper 4, totalling 25 marks. Write your answers in full before checking the mark scheme.
Question 1 (5 marks)
A student places small pieces of four metals into separate test tubes of dilute hydrochloric acid. The results are shown below.
| Metal | Observation |
|---|---|
| Magnesium | Vigorous effervescence, dissolves quickly |
| Zinc | Steady effervescence, dissolves slowly |
| Iron | Slow effervescence, partially dissolves |
| Copper | No reaction |
(a) Place these four metals in order of reactivity, most reactive first. [1]
(b) Explain why copper does not react with dilute hydrochloric acid. [1]
(c) Write the balanced equation for the reaction of zinc with hydrochloric acid. [1]
(d) Predict what would happen if a piece of zinc were placed in copper(II) sulfate solution. Explain your answer. [2]
Mark scheme
(a) Magnesium, zinc, iron, copper [1]
(b) Copper is below hydrogen in the reactivity series, so it is not reactive enough to displace hydrogen from the acid [1].
(c) Zn + 2HCl → ZnCl₂ + H₂ [1]
(d) A displacement reaction would occur. Orange-brown copper metal would be deposited on the zinc [1]. The blue colour of the solution would fade as Cu²⁺ ions are replaced by colourless Zn²⁺ ions. This is because zinc is more reactive than copper, so it displaces copper from the solution [1].
Total: 5 marks
Question 2 (5 marks)
Iron is extracted from iron(III) oxide in a blast furnace using carbon monoxide as the reducing agent.
Fe₂O₃ + 3CO → 2Fe + 3CO₂
(a) State the meaning of the term reduction, as applied to this reaction. [1]
(b) Explain why carbon (or carbon monoxide) can be used to extract iron but not aluminium from their ores. [2]
(c) Name the method used to extract aluminium from its ore. [1]
(d) Explain why recycling aluminium is important, considering its method of extraction. [1]
Mark scheme
(a) Reduction is the loss of oxygen / gain of electrons [1]. In this reaction, iron(III) oxide loses its oxygen / Fe³⁺ gains electrons to form Fe.
(b) Iron is below carbon in the reactivity series, so carbon can reduce iron oxide / remove the oxygen from iron oxide [1]. Aluminium is above carbon in the reactivity series, so carbon is not reactive enough to reduce aluminium oxide [1].
(c) Electrolysis (of molten aluminium oxide / bauxite dissolved in cryolite) [1]
(d) Electrolysis requires large amounts of electrical energy, which is expensive and often generated from fossil fuels. Recycling uses much less energy (about 5% of the energy needed to extract new aluminium), saving costs and reducing environmental impact [1].
Total: 5 marks
Question 3 (5 marks)
A student sets up three experiments to investigate the conditions needed for iron to rust.
| Tube | Contents |
|---|---|
| A | Iron nail in boiled water sealed with oil |
| B | Iron nail in water open to air |
| C | Iron nail with anhydrous calcium chloride (drying agent), sealed |
(a) State in which tube(s) the nail rusts. Explain your answer. [2]
(b) State the chemical name for rust. [1]
(c) State two methods of preventing rusting, one that is a barrier method and one that is sacrificial protection. [2]
Mark scheme
(a) Tube B only [1]. Rusting requires both water and oxygen (air). In tube A, the boiled water has no dissolved oxygen and the oil layer prevents oxygen reaching the water. In tube C, the calcium chloride absorbs moisture so there is no water. Only tube B has both water and oxygen present [1].
(b) Hydrated iron(III) oxide [1]
(c) Barrier method: painting / oiling / greasing / plastic coating / tin plating [1]. Sacrificial protection: attaching blocks of zinc (or magnesium) to the iron / galvanising (coating with zinc) [1].
Total: 5 marks
Question 4 (5 marks)
Steel is an alloy of iron and carbon.
(a) Define the term alloy. [1]
(b) Explain, in terms of particle structure, why steel is harder than pure iron. [2]
(c) State two other examples of alloys and name the metals they contain. [2]
Mark scheme
(a) An alloy is a mixture of a metal with one or more other elements (usually metals or carbon) [1].
(b) In pure iron, the atoms are all the same size and arranged in regular layers that can slide over each other easily [1]. In steel, the carbon atoms are a different size to the iron atoms. They disrupt the regular arrangement, preventing the layers from sliding and making the alloy harder [1].
(c) Any two from: brass (copper and zinc) [1]; bronze (copper and tin) [1]; stainless steel (iron, chromium, and nickel) [1]; solder (tin and lead, or tin and copper) [1].
Total: 5 marks
Question 5 (5 marks)
A student has solutions of copper(II) sulfate, zinc sulfate, and magnesium sulfate, and pieces of copper, zinc, and magnesium metal.
(a) State three combinations of metal and solution that would result in a displacement reaction. [3]
(b) Explain why copper cannot displace zinc from zinc sulfate solution. [1]
(c) Write the ionic equation for the reaction between magnesium and copper(II) sulfate solution. [1]
Mark scheme
(a) Any three of the following: zinc in copper(II) sulfate [1]; magnesium in copper(II) sulfate [1]; magnesium in zinc sulfate [1].
(b) Copper is less reactive than zinc, so it cannot displace zinc from its salt solution / a less reactive metal cannot displace a more reactive metal [1].
(c) Mg(s) + Cu²⁺(aq) → Mg²⁺(aq) + Cu(s) [1]
Total: 5 marks
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