Metal Properties and Reactivity: Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs — examination boards hold copyright in their own papers. Use these alongside the official past papers available free from your board.

Related: Metal Properties and Reactivity revision notes

Tier note: parts marked (0620 Extended, 5070 required) go beyond 0620 Core: the symbol equation for the blast furnace (syllabus 9.6), explaining alloy hardness in terms of structure (9.3), sacrificial protection and galvanising (9.5) and displacement reactions with aqueous metal ions (9.4). Everything else is 0620 Core. 5070 has no tiers, so O Level candidates need all of it.

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Section A

1. List these metals in order of decreasing reactivity: copper, calcium, zinc, potassium, iron. [2]

2. State what you would observe when sodium, calcium and copper are each added to cold water. [3]

Section B

3. Explain how the reactivity of a metal determines its method of extraction, referring to two methods. [4]

4. (Extension beyond this resource’s core scope — blast-furnace extraction detail is covered in Alloys and Extraction of Metals ; included here only as a worked example of question 3’s reactivity-extraction link.) Iron is extracted in the blast furnace.

(a) (0620 Extended, 5070 required) Write the symbol equation for the reduction of iron(III) oxide by carbon monoxide. [2] (b) Explain the role of limestone. [3] (c) Explain why aluminium cannot be extracted this way. [2]

5. Rusting requires both air and water.

(a) Describe an experiment to show that both are needed. [4] (b) (0620 Extended, 5070 required) Explain how galvanising protects iron by two different mechanisms. [4]

6. (0620 Extended, 5070 required) (Extension beyond this resource’s core scope — alloys are covered in Alloys and Extraction of Metals .) Describe the arrangement of atoms in a pure metal and in an alloy (as you would show in a diagram), and use it to explain why an alloy is harder than the pure metal. [3]

7. Magnesium ribbon reacts rapidly with steam, but only very slowly with cold water.

(a) Write the word equation for magnesium’s reaction with steam. [1] (b) State why the same metal can react at very different rates with water and with steam. [1]

8. In an experiment, magnesium reacts vigorously with dilute hydrochloric acid, zinc reacts moderately, and silver shows no reaction at all.

(a) Rank the three metals in order of decreasing reactivity, with reasoning. [2] (b) State which of the three would react with dilute acid to release hydrogen gas, and which would not. [2]

9. Painting, greasing and galvanising can all be used to protect iron from rusting.

(a) Explain why painting and greasing work, and state one limitation they share. [2] (b) (0620 Extended, 5070 required) Explain why galvanising still protects iron even where the coating is scratched, unlike painting or greasing. [2]

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10. (0620 Extended, 5070 required) Zinc powder is added to three separate solutions: copper(II) sulfate, magnesium sulfate and iron(II) sulfate.

(a) State which of the solutions react with zinc, and explain your answer. [2]

(b) Name the products of one of these reactions. [1]

Answers

1. Potassium, calcium, zinc, iron, copper [2 — 1 mark if one pair is transposed].

2. Sodium — melts into a ball, fizzes vigorously and moves rapidly on the surface [1]. Calcium — steady stream of bubbles, sinks then rises, solution turns cloudy [1]. Copper — no reaction [1].

3. A metal more reactive than carbon must be extracted by electrolysis of its molten ore, because carbon cannot reduce it [1] [1]. A metal less reactive than carbon can be reduced by heating with carbon, which is much cheaper [1]; the least reactive metals such as gold occur native and need no extraction [1].

4. (a) Fe₂O₃ + 3CO → 2Fe + 3CO₂ [1], correctly balanced [1]. (b) The limestone decomposes to calcium oxide and carbon dioxide in the heat [1]; the calcium oxide is basic and reacts with the acidic silicon dioxide impurity [1] to form calcium silicate — molten slag, which floats on the iron and is drained off [1].

(c) Aluminium is more reactive than carbon [1], so carbon cannot remove the oxygen from aluminium oxide — electrolysis is required instead [1].

5. (a) Set up three boiling tubes each with an iron nail [1]. Tube 1: air and water — the nail rusts [1]. Tube 2: boiled water with a layer of oil on top, excluding air — no rust [1]. Tube 3: dry air with anhydrous calcium chloride and a bung — no rust [1]. Only the tube with both air and water shows rusting. (b) The zinc layer covers the iron as a barrier [1], so air (oxygen) and water cannot reach the iron [1]. Zinc is more reactive than iron, so even if the coating is scratched the zinc is oxidised in preference [1] — sacrificial protection, which continues to protect the exposed iron [1].

6. In a pure metal the atoms are the same size and arranged in regular layers that can slide over one another [1]. In an alloy, atoms of a different size are introduced [1], which distorts the layers and prevents them sliding, so the alloy is harder [1].

7. (a) magnesium + steam → magnesium oxide + hydrogen [1]. (b) Steam is at a much higher temperature than cold water, and a higher temperature makes the reaction faster [1]. (0620 Extended, not needed for the mark: at the higher temperature more of the colliding particles have energy equal to or greater than the activation energy, so more collisions are successful.)

8. (a) Magnesium > zinc > silver [1]; a more vigorous reaction with the same acid under the same conditions indicates a more reactive metal [1]. (b) Magnesium and zinc would react to release hydrogen gas [1]; silver, being below hydrogen in the reactivity series, would not react at all [1].

9. (a) Both physically exclude oxygen and water from the metal surface, stopping rusting while the coating remains intact [1]; the shared limitation is that once the coating is scratched or damaged, the exposed metal beneath rusts normally [1]. (b) Zinc is more reactive than iron, so where the coating is broken, the zinc corrodes preferentially (sacrificial protection), continuing to protect the iron even without an intact barrier [1] — a mechanism painting and greasing simply don’t have, since neither coating material is more reactive than iron [1].

10. (a) Copper(II) sulfate and iron(II) sulfate react [1], because zinc is more reactive than copper and iron but less reactive than magnesium, and a metal only displaces a less reactive metal from its compound [1]. (b) Zinc sulfate and copper (or: zinc sulfate and iron) [1].

Examiner insight (June 2025): many candidates did not know the order of the reactivity series and picked the wrong metal. Learn the order K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au. Try the real question next: Cambridge IGCSE Chemistry 0620, June 2025, Paper 32, Question 1.

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Where marks are usually lost

• Saying copper reacts slowly with water.
• Omitting the decomposition step for limestone.
• Giving only the barrier explanation for galvanising.
• Saying alloys are harder because the atoms bond more strongly.
• Treating “reacts with water” and “reacts with steam” as the same test — steam supplies more energy, so a metal that barely reacts with cold water can react rapidly with steam.
• Assuming any protective coating gives sacrificial protection — only a coating metal more reactive than iron (such as zinc) does; paint and grease are barrier methods only.