Metals and Reactivity MCQs – 40 Practice Questions with Answers and Explanations

Master the reactivity series, displacement reactions, metal extraction and corrosion with 40 free practice questions. Every question has a full answer and explanation, and the difficulty builds from GCSE and IGCSE core ideas to an A-Level stretch at the end.

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Section 1: The Reactivity Series

Q1. Which list shows metals in order of reactivity, most reactive first?

  • (A) copper, iron, zinc, magnesium
  • (B) magnesium, zinc, iron, copper
  • (C) zinc, magnesium, copper, iron
  • (D) iron, copper, zinc, magnesium
Show Answer

Answer: B – In the reactivity series magnesium is above zinc, which is above iron, which is above copper.

Q2. Which metal reacts most violently with cold water, bursting into a lilac flame?

  • (A) calcium
  • (B) magnesium
  • (C) potassium
  • (D) zinc
Show Answer

Answer: C – Potassium is near the top of the series; it melts, skates on the water and the hydrogen produced catches fire with a lilac flame.

Q3. Calcium reacts steadily with cold water. What are the products?

  • (A) calcium oxide and hydrogen
  • (B) calcium hydroxide and hydrogen
  • (C) calcium hydroxide and oxygen
  • (D) calcium chloride and hydrogen
Show Answer

Answer: B – Ca + 2H2O → Ca(OH)2 + H2. The solution formed is alkaline, and bubbles of hydrogen are given off.

Q4. Magnesium reacts extremely slowly with cold water, but reacts readily when heated in steam. The products are:

  • (A) magnesium oxide and hydrogen
  • (B) magnesium hydroxide and hydrogen
  • (C) magnesium hydroxide and oxygen
  • (D) magnesium oxide and oxygen
Show Answer

Answer: A – Mg + H2O(g) → MgO + H2. Steam is hot enough for magnesium to take oxygen from the water, so the oxide (not the hydroxide) forms.

Q5. Which metal does NOT react with dilute hydrochloric acid?

  • (A) zinc
  • (B) iron
  • (C) copper
  • (D) magnesium
Show Answer

Answer: C – Copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from dilute acids and nothing happens.

Q6. Where does carbon fit in the reactivity series?

  • (A) between aluminium and zinc
  • (B) above potassium
  • (C) below copper
  • (D) between iron and lead
Show Answer

Answer: A – Carbon sits between aluminium and zinc, which is why carbon can reduce the oxides of zinc, iron and copper but not aluminium oxide.

Q7. What is observed when zinc granules are added to dilute sulfuric acid?

  • (A) nothing happens at all
  • (B) the zinc burns with a lilac flame
  • (C) a white precipitate forms instantly
  • (D) bubbles of gas form and the zinc gradually dissolves
Show Answer

Answer: D – Zinc is above hydrogen, so Zn + H2SO4 → ZnSO4 + H2; the fizzing is hydrogen being produced.

Q8. Sodium is stored under oil in the laboratory. Why?

  • (A) it reacts quickly with oxygen and moisture in the air
  • (B) it would melt at room temperature
  • (C) it dissolves in water vapour only
  • (D) oil makes the metal harder
Show Answer

Answer: A – Sodium is so reactive that it tarnishes and reacts with air and moisture; oil forms a barrier that keeps both away from the metal.

Q9. Which list is in order of decreasing reactivity?

  • (A) silver, lead, iron
  • (B) iron, lead, silver
  • (C) lead, silver, iron
  • (D) silver, iron, lead
Show Answer

Answer: B – In the series, iron comes above lead, and lead comes above silver (and gold is below silver, near the very bottom).

Q10. Red-hot iron reacts with steam. The products are:

  • (A) iron hydroxide and hydrogen
  • (B) iron(II) oxide and oxygen
  • (C) magnetite, Fe3O4, and hydrogen
  • (D) no reaction takes place
Show Answer

Answer: C – 3Fe + 4H2O(g) → Fe3O4 + 4H2. Iron is reactive enough to react with steam, but not with cold water.

Section 2: Displacement Reactions

Q11. A piece of zinc is placed in blue copper(II) sulfate solution and left for an hour. What is seen?

  • (A) nothing changes
  • (B) large bubbles of gas are produced
  • (C) the blue colour becomes darker
  • (D) the blue colour fades and a pink-brown coating forms on the zinc
Show Answer

Answer: D – Zinc is more reactive than copper, so Zn + CuSO4 → ZnSO4 + Cu. The blue Cu2+ ions leave the solution, so the colour fades.

Q12. An iron nail left in copper(II) sulfate solution becomes coated. The coating is:

  • (A) iron(II) sulfate
  • (B) copper
  • (C) copper(II) oxide
  • (D) sulfur
Show Answer

Answer: B – Iron displaces copper from its salt: Fe + CuSO4 → FeSO4 + Cu, and the displaced copper metal plates onto the nail.

Q13. Which pair will show NO displacement reaction?

  • (A) magnesium added to zinc sulfate solution
  • (B) zinc added to iron(II) sulfate solution
  • (C) copper added to magnesium sulfate solution
  • (D) iron added to copper(II) sulfate solution
Show Answer

Answer: C – Copper is far less reactive than magnesium, so it cannot take the sulfate ions from magnesium; the other three metals are all more reactive than the metal in the salt.

Q14. The thermite reaction, used to weld railway tracks together, is:

  • (A) aluminium + iron(III) oxide → iron + aluminium oxide
  • (B) iron + aluminium oxide → aluminium + iron(III) oxide
  • (C) aluminium + copper oxide → lead + aluminium oxide
  • (D) aluminium + oxygen → hydrogen + aluminium oxide
Show Answer

Answer: A – Aluminium is more reactive than iron, so 2Al + Fe2O3 → 2Fe + Al2O3; the reaction is so exothermic that the iron formed is molten.

Q15. An unknown metal X displaces copper from copper(II) sulfate solution, but does NOT displace zinc from zinc sulfate solution. Where does X sit in the reactivity series?

  • (A) above zinc
  • (B) between zinc and copper
  • (C) below copper
  • (D) above potassium
Show Answer

Answer: B – X must be more reactive than copper (to displace it) but less reactive than zinc (so zinc stays in its salt), placing X between them.

Q16. Magnesium powder is heated strongly with copper(II) oxide. What happens?

  • (A) no reaction takes place
  • (B) copper displaces magnesium from its oxide
  • (C) the two powders simply melt and mix
  • (D) magnesium reduces the copper(II) oxide to copper, forming magnesium oxide
Show Answer

Answer: D – A more reactive metal can also displace a less reactive metal from its oxide: Mg + CuO → MgO + Cu.

Q17. A piece of silver is dropped into zinc sulfate solution. What happens?

  • (A) silver displaces zinc from the solution
  • (B) the solution turns blue
  • (C) no reaction, because silver is less reactive than zinc
  • (D) hydrogen gas is given off
Show Answer

Answer: C – Displacement only works one way: the added metal must be MORE reactive than the metal already in the compound.

Q18. Copper wire is placed in colourless silver nitrate solution. After a while:

  • (A) nothing changes
  • (B) the solution turns blue and grey-silver crystals form on the wire
  • (C) silver displaces copper from the wire
  • (D) oxygen gas is released
Show Answer

Answer: B – Copper is more reactive than silver: Cu + 2AgNO3 → Cu(NO3)2 + 2Ag. The blue colour is the copper(II) ions entering solution.

Q19. Which metal could be used to reduce iron(III) oxide in a thermite-style reaction?

  • (A) aluminium
  • (B) copper
  • (C) lead
  • (D) silver
Show Answer

Answer: A – Only a metal above iron in the series can take its oxygen away; copper, lead and silver are all below iron.

Q20. Metal M displaces lead from lead(II) nitrate solution, but does not displace iron from iron(II) sulfate solution. Metal M is:

  • (A) more reactive than both iron and lead
  • (B) less reactive than both iron and lead
  • (C) between lead and copper in the series
  • (D) between iron and lead in the series
Show Answer

Answer: D – M beats lead but loses to iron, so its position is below iron and above lead – exactly how displacement results are used to place an unknown metal.


Section 3: Extraction of Metals

Q21. Aluminium is extracted by electrolysis of its molten oxide, not by heating with carbon, because:

  • (A) aluminium is less reactive than carbon
  • (B) aluminium is more reactive than carbon, so carbon cannot reduce aluminium oxide
  • (C) aluminium oxide does not contain oxygen
  • (D) carbon is more expensive than electricity
Show Answer

Answer: B – Metals above carbon in the series (potassium down to aluminium) have oxides too stable for carbon reduction, so electrolysis is used instead.

Q22. In the extraction of aluminium, the aluminium oxide is dissolved in molten cryolite. The cryolite:

  • (A) lowers the melting point of the mixture, so less energy is needed to keep it molten
  • (B) acts as a catalyst for the reaction
  • (C) supplies the carbon for the electrodes
  • (D) removes silica impurities from the bauxite
Show Answer

Answer: A – Pure aluminium oxide melts above 2000°C; dissolving it in cryolite lets the cell run at about 950°C, hugely cutting energy costs (and improving conductivity).

Q23. What is the equation for the reaction at the negative electrode (cathode) in the electrolysis of molten aluminium oxide?

  • (A) Al3+ + 3e− → Al
  • (B) 2O2− → O2 + 4e−
  • (C) Al → Al3+ + 3e−
  • (D) O2 + 4e− → 2O2−
Show Answer

Answer: A – Positive aluminium ions move to the negative cathode and gain electrons to form molten aluminium metal, which is tapped off at the bottom of the cell.

Q24. The carbon anodes in an aluminium extraction cell have to be replaced regularly because:

  • (A) they melt at the working temperature
  • (B) they slowly dissolve in the cryolite
  • (C) the oxygen produced at the anode reacts with the carbon to form carbon dioxide, so the anodes wear away
  • (D) aluminium builds up on them and blocks the current
Show Answer

Answer: C – Oxide ions discharge to give oxygen at the positive anode, and at 950°C this oxygen burns the carbon anode away as CO2 – one reason aluminium extraction is expensive.

Q25. In the blast furnace, coke first burns in hot air and the carbon dioxide then reacts with more coke. Which gas actually removes the oxygen from iron(III) oxide?

  • (A) oxygen
  • (B) carbon dioxide
  • (C) carbon monoxide
  • (D) nitrogen
Show Answer

Answer: C – C + O2 → CO2, then CO2 + C → 2CO. It is the carbon monoxide that reduces the iron oxide as it rises up the furnace.

Q26. The main reduction step in the blast furnace is: Fe2O3 + 3CO → 2Fe + 3CO2. In this reaction, the reducing agent is:

  • (A) iron(III) oxide
  • (B) iron
  • (C) carbon dioxide
  • (D) carbon monoxide
Show Answer

Answer: D – Carbon monoxide takes the oxygen from the iron(III) oxide and is itself oxidised to carbon dioxide, so CO is the reducing agent.

Q27. Limestone (calcium carbonate) is added to the blast furnace to:

  • (A) cool the furnace down
  • (B) decompose to calcium oxide, which reacts with sandy silicon dioxide impurities to form molten slag
  • (C) act as the main fuel
  • (D) oxidise the molten iron
Show Answer

Answer: B – CaCO3 → CaO + CO2, then CaO + SiO2 → CaSiO3. The slag floats on the iron and carries the acidic impurities away.

Q28. The slag formed in the blast furnace consists mainly of:

  • (A) calcium carbonate
  • (B) calcium oxide
  • (C) calcium silicate
  • (D) iron(III) oxide
Show Answer

Answer: C – Slag is calcium silicate, CaSiO3, made when the basic calcium oxide neutralises the acidic silicon dioxide impurity in the ore.

Q29. Black copper(II) oxide heated with carbon powder turns pink-brown. Copper is produced because:

  • (A) copper is more reactive than carbon
  • (B) copper(II) oxide acts as a catalyst
  • (C) the carbon dioxide formed does the reducing
  • (D) carbon is more reactive than copper, so it removes the oxygen from copper(II) oxide
Show Answer

Answer: D – 2CuO + C → 2Cu + CO2. Carbon reduction works for all metals below carbon in the series, such as zinc, iron and copper.

Q30. Gold is sometimes found in the ground as the pure metal (native). This is because gold:

  • (A) is so unreactive that it does not combine with other elements in the Earth
  • (B) is always extracted by electrolysis
  • (C) reacts very quickly with air and water
  • (D) is only ever found as a soluble salt
Show Answer

Answer: A – Gold sits at the very bottom of the reactivity series, so it stays as the free metal over geological time and needs no chemical extraction.

Section 4: Corrosion, Alloys and Recycling (with A-Level Stretch)

Q31. Three identical iron nails are left in: (1) dry air, (2) boiled distilled water covered with oil, (3) ordinary tap water open to the air. Only nail 3 rusts, showing that rusting requires:

  • (A) water only
  • (B) oxygen only
  • (C) both water and oxygen together
  • (D) dissolved salt
Show Answer

Answer: C – Nail 1 had oxygen but no water, nail 2 had water but the boiling and oil layer kept oxygen out; rusting needs both at the same time.

Q32. Blocks of magnesium are bolted to the iron hull of a ship to protect it from rusting. This sacrificial protection works because:

  • (A) magnesium is less reactive than iron
  • (B) magnesium is more reactive than iron, so it corrodes instead of the iron
  • (C) magnesium forms a waterproof paint layer
  • (D) magnesium neutralises acids in seawater
Show Answer

Answer: B – The more reactive metal is sacrificed: magnesium reacts with the water and oxygen preferentially, and the iron hull stays intact until the blocks are used up.

Q33. In terms of electrons, sacrificial protection of iron by magnesium works because:

  • (A) iron atoms lose electrons to magnesium ions
  • (B) oxygen takes electrons from the iron surface faster
  • (C) magnesium ions gain electrons from the iron
  • (D) magnesium atoms lose electrons more readily than iron atoms, so the iron is not oxidised
Show Answer

Answer: D – Rusting starts with iron atoms losing electrons (oxidation). Magnesium loses electrons even more easily, so it is oxidised in place of the iron.

Q34. Stainless steel, used for cutlery and surgical instruments, is an alloy of iron with:

  • (A) tin
  • (B) chromium (and usually some nickel)
  • (C) zinc
  • (D) lead
Show Answer

Answer: B – The chromium forms a thin, protective oxide layer on the surface, which stops the iron underneath from rusting.

Q35. Brass, used for musical instruments and door fittings, is an alloy of:

  • (A) copper and zinc
  • (B) copper and tin
  • (C) iron and chromium
  • (D) lead and tin
Show Answer

Answer: A – Brass is copper mixed with zinc; it is harder than pure copper and does not corrode easily.

Q36. Bronze, one of the first alloys ever made, consists of:

  • (A) copper and zinc
  • (B) iron and carbon
  • (C) aluminium and copper
  • (D) copper and tin
Show Answer

Answer: D – Bronze is copper + tin – do not mix it up with brass, which is copper + zinc.

Q37. Alloys are usually harder than the pure metals they are made from because:

  • (A) all the atoms are the same size, so layers slide easily
  • (B) alloys always have lower melting points
  • (C) the different-sized atoms distort the regular layers, so the layers cannot slide over each other easily
  • (D) alloys always contain carbon
Show Answer

Answer: C – In a pure metal the neat layers slide, making it soft; atoms of a second element of a different size jam the layers in place, making the alloy harder and stronger.

Q38. Titanium is extracted by the Kroll process, in which magnesium reduces titanium(IV) chloride. Carbon cannot be used for this extraction because:

  • (A) magnesium is an unreactive metal
  • (B) titanium is a very unreactive metal
  • (C) carbon reduction produces pure titanium easily
  • (D) titanium is more reactive than carbon (and reacts with it), so a more reactive metal such as magnesium must do the reducing
Show Answer

Answer: D – TiCl4 + 2Mg → Ti + 2MgCl2. Carbon reduction fails for titanium, which is one reason titanium is so expensive despite being a common element.

Q39. The biggest advantage of recycling aluminium cans instead of extracting new aluminium from bauxite is that recycling:

  • (A) uses only a small fraction of the energy needed for electrolysis, and conserves the ore
  • (B) produces a completely different metal
  • (C) releases more carbon dioxide
  • (D) needs no collection or sorting
Show Answer

Answer: A – Remelting scrap aluminium uses about 5% of the energy of extracting it by electrolysis. The limits are collection, sorting and contamination of the scrap.

Q40. Looked at as redox, extracting any metal from its oxide is a reduction because the metal ions:

  • (A) lose electrons
  • (B) gain electrons to form neutral metal atoms
  • (C) gain oxygen atoms
  • (D) share electrons with the carbon
Show Answer

Answer: B – Reduction is gain of electrons: Mn+ + ne− → M. Whether carbon or a current does the job, the metal ion is always reduced during extraction.

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