O LevelChemistryCambridge (CIE)Exam Questions9. Metals9.5 Corrosion of Metals

Corrosion of Metals (Cambridge (CIE) O Level Chemistry): Exam Questions

Exam code: 5070

3 hours36 questions

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9.5 Corrosion of Metals

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1
1 mark

The diagrams below show some of the uses of iron.

In which of these uses is iron most likely to rust?

Four labelled line drawings of iron objects, A to D. A is a gate with hinges, captioned "Iron hinges on a gate". B is a railing fence drawn in solid black, captioned "Painted iron fence". C is a bucket with a handle, captioned "Iron bucket electroplated with zinc". D is two pylons carrying overhead cables, captioned "Iron cored aluminium electricity cables".

    Choose your answer

    2
    1 mark

    A student prepared four iron nails as explained below in an experiment to investigate rusting. She allowed the nails to rest in individual test tubes in a laboratory for one week.

    Which nail will show the greatest amount of rust?

    • Dipped in water and allowed to dry.

    • Dipped in paint and allowed to dry.

    • Coated in grease.

    • Galvanised with zinc.

    Choose your answer

    3
    1 mark

    The diagram shows the experimental set-up a student used to investigate the composition of air. The student left the apparatus in the laboratory and observed that the water level had risen inside the test tube after one week.

    A test-tube standing upright in a trough, drawn in cross-section. A plug of damp iron fibre sits at the closed top of the tube, labelled "Damp iron fibre". The trough and the lower part of the tube are filled with a shaded liquid, labelled "Water". The liquid inside the tube is level with the liquid in the trough.

    Which statement explains why the water level rose?

    • Nitrogen monoxide was produced.

    • Iron oxide was produced.

    • The temperature of the water increased.

    • Sulfur dioxide was produced.

    Choose your answer

    4
    1 mark

    An iron gate is left outdoors.

    Which method will not slow down the rate of rusting of the gate?

    • attaching blocks of magnesium to it

    • bolting strips of copper to it

    • coating it with zinc

    • painting it

    Choose your answer

    5
    1 mark

    Iron rusts to form hydrated iron(III) oxide.

    Which pair of substances must both be present for iron to rust?

    • carbon dioxide and water

    • nitrogen and oxygen

    • oxygen and water

    • oxygen and carbon dioxide

    Choose your answer

    1
    1 mark

    Attaching pieces of magnesium to underground iron pipes can protect the iron from corrosion.

    Which reaction protects the iron from corrosion?

    • Fe2+(aq) + 2e– → Fe(s)

    • Fe(s) → Fe2+(aq) + 2e–

    • Mg2+(aq) + 2e–  → Mg(s)

    • Mg(s) → Mg2+(aq) + 2e–

    Choose your answer

    2
    1 mark

    Four test-tubes each contain an identical iron nail. The table shows how each nail is prepared and what else is in the tube.

    tube

    contents

    A

    dry air, closed with a stopper

    B

    air, and the nail is coated in grease

    C

    tap water and air

    D

    tap water, and the nail is coated in paint

    The tubes are left in a laboratory for two weeks.

    In which tube will the nail rust?

      Choose your answer

      3
      1 mark

      Four statements about the rusting of iron are shown.

      1. Rusting needs both oxygen and water to be present.

      2. Rust is an alloy of iron and oxygen.

      3. Sacrificial protection uses a metal that is less reactive than iron.

      4. Grease prevents rusting by forming a barrier.

      Which two statements are correct?

      • 1 and 4

      • 1 and 3

      • 2 and 3

      • 3 and 4

      Choose your answer

      4
      1 mark

      Two sheets of steel are coated, one with zinc and one with tin.

      Both coatings are scratched through to the steel underneath. The sheets are then left outdoors.

      Which row describes what happens to the steel at the scratches?

      zinc-coated sheet

      tin-coated sheet

      A

      rusts

      rusts

      B

      rusts

      does not rust

      C

      does not rust

      rusts

      D

      does not rust

      does not rust

        Choose your answer

        5
        1 mark

        Iron can be protected from rusting in several ways.

        Which method protects iron both by acting as a barrier and by sacrificial protection?

        • connecting the iron to a block of magnesium

        • coating the iron with tin

        • coating the iron with zinc

        • painting the iron

        Choose your answer

        1
        1 mark

        Small blocks of zinc are attached to ship hulls which are commonly made from steel, an alloy of iron. This is done to prevent the hull from rusting.

        Which statement explains this process?

        • Zinc is higher up on the reactivity series than iron so has a higher tendency to become reduced.

        • Zinc is lower down on the reactivity series than iron so has a higher tendency to become reduced.

        • Zinc is higher up on the reactivity series than iron so has a higher tendency to become oxidised.

        • Zinc is lower down on the reactivity series than iron so has a higher tendency to become oxidised.

        Choose your answer

        2
        1 mark

        An iron nail is placed in a test-tube of water that has been boiled and then allowed to cool.

        A layer of oil is poured onto the surface of the water.

        After two weeks, the nail has not rusted.

        Which statement explains why the nail has not rusted?

        • The oil stops the water from reaching the nail.

        • Boiling the water killed the bacteria that cause rusting.

        • Boiling removed the dissolved air, and the oil stops air dissolving back in.

        • Boiling raised the temperature of the water, so the rusting was over before the two weeks ended.

        Choose your answer

        3
        1 mark

        A student sets up four test-tubes, each containing an identical iron nail.

        tube

        contents

        where it is kept

        1

        dry air, closed with a stopper

        laboratory bench

        2

        completely filled with boiled water, closed with a stopper

        laboratory bench

        3

        tap water and air

        laboratory bench

        4

        tap water and air

        warm cupboard

        Which two tubes should be compared to show that water is needed for rusting?

        • 1 and 2

        • 1 and 3

        • 2 and 3

        • 3 and 4

        Choose your answer

        4
        1 mark

        A test-tube contains an iron nail in dry air. The tube is closed with a stopper. The nail does not rust.

        A student says:

        "The stopper stops oxygen getting into the tube, so the nail cannot rust."

        Why is the student's explanation wrong?

        • The stopper does not form an airtight seal.

        • The tube already contains oxygen, so the stopper is there to keep water vapour out.

        • Oxygen is not needed for rusting, only water is.

        • The stopper is there to stop water vapour escaping from the tube.

        Choose your answer

        5
        1 mark

        A sheet of iron is galvanised by coating it with zinc.

        Four statements about the coated sheet are shown.

        1. The zinc protects the iron both as a barrier and by sacrificial protection.

        2. The zinc is gradually used up as it protects the iron.

        3. The zinc protects the iron only while the zinc layer is unbroken.

        4. The zinc coating is an alloy of zinc and iron.

        Which two statements are correct?

        • 1 and 2

        • 1 and 3

        • 2 and 4

        • 3 and 4

        Choose your answer