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A quick practice test on Metals and Non-metals to check how ready you are for the chapter. Attempt it fully on paper first — give yourself about 45 minutes — then reveal the answer key at the bottom to mark yourself. Total: 20 marks. Need a refresher first? Read the Metals and Non-metals notes.
Section A — Objective (5 × 1 mark)
- Which of the following metals is stored under kerosene?
(a) Copper (b) Sodium (c) Zinc (d) Silver - An iron nail is left in copper sulphate solution for about 20 minutes. The correct observation is:
(a) the blue solution turns pale green and a brown deposit forms on the nail (b) the blue solution stays blue and nothing changes (c) the solution turns colourless and a silvery deposit forms (d) the nail dissolves completely, leaving a blue solution - The correct order of decreasing reactivity is:
(a) Zn > Fe > Cu > Ag (b) Cu > Zn > Fe > Ag (c) Ag > Cu > Fe > Zn (d) Fe > Zn > Ag > Cu - Which statement about ionic compounds is not correct?
(a) They generally have high melting points. (b) They conduct electricity in the molten state. (c) They are generally soluble in petrol and kerosene. (d) They exist as hard, brittle solids. - Assertion (A): Aluminium does not corrode as readily as iron, even though aluminium is more reactive than iron.
Reason (R): Aluminium forms a thin, hard, tightly adhering oxide layer on its surface that protects the metal underneath.
(a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true, R is false. (d) A is false, R is true.
Section B — Short Answer (5 × 2 marks)
- Write balanced chemical equations for: (i) the reduction of zinc oxide to zinc using carbon; (ii) the conversion of zinc carbonate to zinc oxide by calcination.
- Explain why ionic compounds conduct electricity in the molten state but not in the solid state.
- A student has strips of copper, zinc, iron and magnesium, and a solution of iron(II) sulphate. Which of these metals will displace iron from the solution? Give a reason.
- What is galvanisation? Explain how it protects iron from rusting even when the coating gets scratched.
- Give reasons: (i) Metal wires are used for electrical connections. (ii) Sulphur cannot be beaten into thin sheets.
Section C — Long Answer (1 × 5 marks)
- A metal M occurs in nature mainly as its sulphide ore. The ore is first concentrated, then converted into the oxide, the oxide is reduced to the metal, and the metal is finally refined by electrolysis.
(i) Name the process used to convert a sulphide ore into the oxide, and write a balanced equation using zinc sulphide as the example. (2)
(ii) Name the process used to convert a carbonate ore into the oxide, and state one way in which it differs from the process in (i). (2)
(iii) In the electrolytic refining of M, state what is used as the anode and what is used as the cathode. (1)
Show the Full Answer Key
Section A
1. (b) Sodium. Sodium reacts vigorously with the oxygen and moisture of air at room temperature and can catch fire, so it is kept under kerosene, which keeps air and water away and does not react with it.
2. (a). Iron is above copper in the reactivity series, so it displaces copper: Fe + CuSO4 → FeSO4 + Cu. The blue Cu2+ colour fades to the pale green of Fe2+, and the displaced copper settles on the nail as a brown coating. (“Reddish-brown” is equally acceptable.)
3. (a) Zn > Fe > Cu > Ag. In the reactivity series zinc lies above iron, iron above copper, and copper above silver. Option (c) is the same list in increasing order.
4. (c). Ionic compounds dissolve in water but are insoluble in petrol, kerosene and similar organic solvents, so (c) is the false statement. The other three are all genuine properties.
5. (a). Aluminium really is above iron in the reactivity series, so A is true. The Al2O3 layer that forms is thin, hard and sticks tightly to the surface, sealing the metal below — unlike rust, which is flaky and lets corrosion continue. R is true and is exactly why A happens.
Section B
6. (i) ZnO + C (heat) → Zn + CO — carbon is the reducing agent. (2ZnO + C → 2Zn + CO2 is an equally correct alternative.)
(ii) ZnCO3 (heat) → ZnO + CO2.
7. In the solid, the ions are locked in fixed positions in the crystal lattice by strong electrostatic forces, so there are no charge carriers free to move and no current flows. On melting, the heat overcomes these forces, the lattice breaks down and the ions become free to move towards the oppositely charged electrodes — these moving ions carry the current.
8. Zinc and magnesium. Both lie above iron in the reactivity series, so each can displace iron from iron(II) sulphate:
Zn + FeSO4 → ZnSO4 + Fe Mg + FeSO4 → MgSO4 + Fe
Copper lies below iron and cannot displace it; an iron strip in an iron salt gives no displacement at all.
9. Galvanisation is coating iron or steel with a thin layer of zinc, usually by dipping the cleaned article in molten zinc. Zinc is more reactive than iron, so even if the coating is scratched and the iron is exposed, the zinc is oxidised in preference to the iron — it corrodes sacrificially. The iron underneath is protected as long as zinc remains in contact with it.
10. (i) Metals have free (delocalised) electrons that move through the metal, making them good conductors of electricity, and they are ductile, so they can be drawn into thin wires. (ii) Sulphur is a non-metal — it is brittle and non-malleable, so on hammering it shatters into pieces instead of spreading into a sheet.
Section C
11. (i) Roasting — strongly heating the sulphide ore in the presence of excess air.
2ZnS + 3O2 (heat) → 2ZnO + 2SO2
(ii) Calcination — ZnCO3 → ZnO + CO2. It differs from roasting in that calcination is carried out on carbonate ores in the absence or limited supply of air and gives off carbon dioxide, whereas roasting is carried out on sulphide ores in excess air and gives off sulphur dioxide.
(iii) The anode is a thick block of the impure metal M and the cathode is a thin strip of pure metal M, with a solution of a salt of M as the electrolyte. On passing current, M dissolves from the anode and pure M is deposited on the cathode; the impurities settle below the anode as anode mud.
Score it honestly, then go back to only the questions you got wrong — one chapter fixed properly today is worth more than three skimmed tomorrow.