Metallic Materials

19 Grade 7 Pre-Technical Studies questions on Metallic Materials, with worked marking schemes. 19 questions are available on this topic in full.

1. Question 1

   4 marks

   A learner in the workshop is sorting metals collected for a recycling project and notices that some metals are attracted to a magnet while others are not.

   (a) Differentiate between ferrous and non-ferrous metals. (2 marks)

   (b) Give one example of a ferrous metal and one example of a non-ferrous metal. (2 marks)

   (4 marks)

   Marking scheme

   (a) Ferrous metals are metals that contain iron and are therefore attracted to a magnet, while non-ferrous metals are metals that do not contain iron and are not attracted to a magnet. (2 marks) (b) Ferrous metal example (1 mark): steel / cast iron / wrought iron. Non-ferrous metal example (1 mark): aluminium / copper / brass / lead / zinc.

2. Question 2

   4 marks

   A learner in the workshop is sorting metals into ferrous and non-ferrous groups before starting a project.

   (a) State the difference between a ferrous metal and a non-ferrous metal. (2 marks)

   (b) Give two examples of ferrous metals the learner is likely to find in the workshop. (2 marks)

   (4 marks)

   Marking scheme

   (a) A ferrous metal is a metal that contains iron and is therefore usually magnetic and rusts when exposed to moisture, while a non-ferrous metal does not contain iron, is generally not attracted by a magnet and does not rust easily. (2 marks) (b) Examples of ferrous metals (any two): mild steel; cast iron; wrought iron; high carbon steel. (2 marks)

3. Question 3

   1 mark

   Which of the following is a non-ferrous metal?

   A. Mild steel

   B. Wrought iron

   C. Copper

   D. Cast iron

   (1 mark)

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4. Question 4

   1 mark

   Electrical cables use copper for the conducting wire mainly because copper is:

   A. Very cheap and brittle

   B. A good conductor of electricity

   C. A poor conductor of electricity

   D. Non-metallic

   (1 mark)

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5. Question 5

   1 mark

   A learner is choosing a metal to make electrical wires for a project. Which property of copper makes it the best choice?

   A. It is a poor conductor of electricity

   B. It is a good conductor of electricity

   C. It cannot be drawn into wires

   D. It rusts very quickly in air

   (1 mark)

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6. Question 6

   1 mark

   A learner observes that an old iron gate left in the rain has developed a reddish-brown flaky coating. What has happened to the iron?

   A. It has rusted due to reaction with moisture and air

   B. It has melted because of the cold rain

   C. It has turned into copper

   D. It has become a non-metal

   (1 mark)

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7. Question 7

   1 mark

   A learner observes that a metal object rusts when left in the rain. This metal is most likely:

   A. Copper

   B. Brass

   C. A ferrous metal

   D. Aluminium

   (1 mark)

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8. Question 8

   4 marks

   A jua kali artisan wants to make a decorative item that will not rust and will keep a shiny golden appearance. Recommend a suitable metal or alloy and justify your choice.

   (4 marks)

   Marking scheme

   Recommend brass (2 marks). Justification (2 marks): brass is a non-ferrous alloy that does not rust/resists corrosion, has an attractive golden/shiny colour, and is malleable so it can be shaped into decorative items.

9. Question 9

   1 mark

   Metallic materials are broadly divided into ferrous and non-ferrous metals. The main characteristic of a ferrous metal is that it:

   A. Contains no iron

   B. Contains iron

   C. Cannot be magnetised

   D. Is always a liquid

   (1 mark)

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10. Question 10

    4 marks

    (a) Differentiate between ferrous and non-ferrous metals.

    (b) Give one example of each.

    (4 marks)

    Marking scheme

    (a) Ferrous metals contain iron (and are usually magnetic and rust), while non-ferrous metals do not contain iron (usually resist rust and are non-magnetic) (2 marks). (b) Ferrous example (1 mark): mild steel/cast iron/wrought iron. Non-ferrous example (1 mark): copper/aluminium/brass/zinc/lead.

11. Question 11

    1 mark

    A learner observes that an iron gate left in the rain develops a reddish-brown flaky coating. What is this process called, and how can it be prevented?

    A. Melting; prevented by heating

    B. Rusting; prevented by painting or oiling the metal

    C. Bending; prevented by cooling

    D. Drawing; prevented by stretching

    (1 mark)

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12. Question 12

    1 mark

    The property of a metal that allows it to be hammered or rolled into thin sheets without breaking is called:

    A. Ductility

    B. Conductivity

    C. Hardness

    D. Malleability

    (1 mark)

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13. Question 13

    1 mark

    Which of the following is the best method of protecting a mild steel gate from rusting?

    A. Washing it with plain water daily

    B. Leaving it exposed to rain

    C. Painting the surface

    D. Wrapping it in wet cloth

    (1 mark)

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14. Question 14

    1 mark

    Which property of metals allows them to be drawn into thin wires?

    A. Brittleness

    B. Ductility

    C. Elasticity

    D. Transparency

    (1 mark)

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15. Question 15

    3 marks

    State three properties of metals that make them suitable for making cooking sufurias (pots).

    (3 marks)

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16. Question 16

    1 mark

    Which metal is commonly used to galvanise steel iron sheets so as to protect them from rusting?

    A. Silver

    B. Lead

    C. Gold

    D. Zinc

    (1 mark)

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17. Question 17

    6 marks

    Explain three ways in which metals can be protected from corrosion.

    (6 marks)

    Marking scheme

    Any 3 explained (2 marks each): Painting - a coat of paint seals the metal from air and moisture; Galvanising - coating with zinc protects the steel underneath; Oiling/greasing - a film of oil keeps out moisture; Electroplating - coating with another metal (e.g. chrome); Enamelling/coating with plastic - forms a protective layer. Award 1 mark for naming, 1 for explanation.

18. Question 18

    1 mark

    Brass is an example of an alloy. An alloy is best defined as a material made by:

    A. Painting a metal surface

    B. Combining two or more metals, or a metal with another element

    C. Mixing a metal with water

    D. Melting a single pure metal

    (1 mark)

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19. Question 19

    1 mark

    A learner is asked to choose a metal for making electrical wires because it conducts electricity very well and can be drawn into thin strands. Which metal is most suitable?

    A. Copper

    B. Cast iron

    C. Lead

    D. Tin

    (1 mark)

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