Metals and Alloys

29 Grade 9 Integrated Science questions on Metals and Alloys, with worked marking schemes. 29 questions are available on this topic in full.

1. Question 1

   1 mark

   A jua kali artisan mixes copper and tin to make a stronger, harder material for casting ornaments. The material he produces is an example of which alloy?

   A. Brass

   B. Bronze

   C. Steel

   D. Solder

   (1 mark)

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2. Question 2

   3 marks

   State three advantages of alloys over pure metals.

   (3 marks)

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3. Question 3

   4 marks

   Alloys are widely used in Kenya in building and manufacturing. (a) Define the term alloy. (2 marks) (b) State one alloy and give one use of that alloy in daily life. (2 marks)

   (4 marks)

   Marking scheme

   (a) An alloy is a mixture/combination of two or more elements, at least one of which is a metal (2). (b) Any correct pair, e.g. Steel (1) - used for construction/beams/vehicle bodies/tools (1); or Bronze - statues/ornaments; or Brass - padlocks/instruments (accept any valid alloy and matching use).

4. Question 4

   1 mark

   A farmer notices that a painted metal gate does not rust while an unpainted one rusts quickly. Painting prevents rusting mainly because it:

   A. Increases the metal's density

   B. Makes the metal harder

   C. Adds more iron to the surface

   D. Keeps out air and water

   (1 mark)

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5. Question 5

   1 mark

   Steel is an alloy made mainly from

   A. iron and carbon

   B. aluminium and magnesium

   C. gold and silver

   D. copper and zinc

   (1 mark)

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6. Question 6

   5 marks

   Mabati (iron roofing sheets) are galvanised before being sold. (a) State what is meant by galvanising. (2 marks) (b) Explain how galvanising protects the iron sheets from rusting. (3 marks)

   (5 marks)

   Marking scheme

   (a) Galvanising is the coating of iron/steel with a layer of zinc (2). (b) The zinc layer prevents air/oxygen and water/moisture from reaching the iron surface (1); even if the coating is scratched, the more reactive zinc corrodes/reacts in preference to the iron (sacrificial protection) (1); this keeps the iron protected from rusting (1).

7. Question 7

   4 marks

   Name the alloy formed from each of the following combinations and state one use of each:

   (a) Copper and tin

   (b) Iron and carbon

   (4 marks)

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8. Question 8

   1 mark

   An alloy is a

   A. pure metal

   B. mixture of a metal with one or more other metals or non-metals

   C. non-metal mixed with a non-metal

   D. compound of two metals

   (1 mark)

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9. Question 9

   1 mark

   When a metal spoon is struck against a plate it produces a ringing sound. The property that allows metals to produce a ringing sound when struck is called:

   A. Sonority

   B. Conductivity

   C. Ductility

   D. Malleability

   (1 mark)

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10. Question 10

    1 mark

    During a practical lesson, a group heats a metal until it becomes a bright orange colour and hammers it into a thin sheet without it breaking. Which property of the metal is being demonstrated?

    A. Sonority

    B. Brittleness

    C. Malleability

    D. Low density

    (1 mark)

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11. Question 11

    4 marks

    (a) Define the term alloy. (2 marks)

    (b) State two reasons why brass (an alloy of copper and zinc) is preferred to pure copper for making items such as door handles and ornaments. (2 marks)

    (4 marks)

    Marking scheme

    (a) An alloy is a mixture (or homogeneous combination) of a metal with one or more other elements, usually other metals or carbon, made to improve the properties of the metal. (b) Any two of: brass is harder/stronger than pure copper; brass is more resistant to corrosion/tarnishing (keeps its shine longer than pure copper); brass has an attractive golden appearance; brass is more durable and wears less.

12. Question 12

    1 mark

    A student leaves an iron nail in a jar of moist air for two weeks and observes a brown flaky layer forming on it. Which two substances are mainly responsible for this change?

    A. Carbon dioxide and oxygen

    B. Water and sunlight

    C. Oxygen and water

    D. Nitrogen and water

    (1 mark)

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13. Question 13

    1 mark

    Brass is an alloy of copper and

    A. zinc

    B. tin

    C. carbon

    D. nickel

    (1 mark)

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14. Question 14

    1 mark

    A jeweller chooses gold to make ornaments because it stays shiny and does not tarnish over time. Which property of gold makes it especially suitable for jewellery?

    A. Low melting point

    B. High density

    C. Good sonority

    D. Resistance to corrosion

    (1 mark)

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15. Question 15

    4 marks

    A learner sets up an experiment to investigate the conditions necessary for iron to rust. She places clean iron nails in three test tubes: Tube A contains water only, Tube B contains dry air with a drying agent, and Tube C contains both air and water. (a) State the tube in which the nails will rust most. (2 marks) (b) Explain why the nails in Tube B do not rust. (2 marks)

    (4 marks)

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16. Question 16

    6 marks

    State any three physical properties of metals that make them suitable for the manufacture of cooking pots (sufuria). For each property, give a reason. (6 marks)

    (6 marks)

    Marking scheme

    Any three of: Good conductors of heat (1) - allows quick, even heating of food (1); Malleable (1) - can be shaped/hammered into pot form (1); High melting point (1) - do not melt at cooking temperatures (1); Strong/durable (1) - withstand handling without breaking (1). (Max 6 marks)

17. Question 17

    1 mark

    Bronze is an alloy of

    A. lead and tin

    B. iron and carbon

    C. copper and tin

    D. copper and zinc

    (1 mark)

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18. Question 18

    1 mark

    A learner is given four samples of pure metals and asked to identify which one is the best conductor of electricity for making household wiring. Which metal should the learner choose?

    A. Copper

    B. Lead

    C. Aluminium

    D. Iron

    (1 mark)

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19. Question 19

    1 mark

    Roofing sheets (mabati) used on many Kenyan houses are made from iron sheets coated with zinc to prevent them from rusting. This coating process is known as:

    A. Alloying

    B. Smelting

    C. Tempering

    D. Galvanising

    (1 mark)

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20. Question 20

    1 mark

    Rusting of iron can be prevented by

    A. exposing it to air

    B. painting or galvanising

    C. heating the iron

    D. adding water

    (1 mark)

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21. Question 21

    4 marks

    A metalworker makes jewellery and cooking pots from different metals and alloys.

    (a) State two physical properties of metals that make them suitable for making cooking pots. (2 marks)

    (b) Give one reason why an alloy such as bronze is often preferred to a pure metal. (2 marks)

    (4 marks)

    Marking scheme

    (a) Any two of: metals are good conductors of heat (so heat passes quickly to the food); they have high melting points (so they do not melt while cooking); they are malleable (can be shaped into pots); they are strong/tough/durable. (2 marks) (b) An alloy such as bronze is harder/stronger and more durable than the pure metal (copper), and is more resistant to corrosion, making it longer-lasting. (Any one valid reason, 2 marks)

22. Question 22

    5 marks

    (a) Define the term 'alloy'. (1 mark)

    (b) State the two main metals that are mixed to make brass. (2 marks)

    (c) Give one reason why alloys are often used in place of pure metals. (2 marks)

    (5 marks)

    Marking scheme

    (a) An alloy is a mixture of a metal with one or more other elements (which may be metals or non-metals). (b) Copper and zinc. (c) Any one, well explained: alloys are usually stronger/harder than the pure metal; alloys can be more resistant to corrosion/rusting; alloys may be less reactive or more durable than the pure metal.

23. Question 23

    1 mark

    Which of the following is the MAIN reason alloys such as steel are often preferred to their pure parent metals in construction?

    A. Alloys are always cheaper to buy

    B. Alloys always conduct heat better

    C. Alloys are usually stronger and harder

    D. Alloys have a lower melting point

    (1 mark)

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24. Question 24

    1 mark

    An electric cable is made by drawing copper into thin, long wires. The property of copper that allows it to be drawn into wires is:

    A. Malleability

    B. Sonority

    C. Ductility

    D. Brittleness

    (1 mark)

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25. Question 25

    1 mark

    Which property makes metals suitable for making cooking pots?

    A. Poor conductors of heat

    B. Low melting point

    C. Good conductors of heat

    D. Brittle nature

    (1 mark)

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26. Question 26

    1 mark

    Alloys are often preferred over pure metals because they are

    A. less useful in construction

    B. harder and more resistant to corrosion

    C. softer and weaker

    D. more expensive

    (1 mark)

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27. Question 27

    5 marks

    (a) Define the term alloy. (2 marks)

    (b) State two reasons why metals are mixed to form alloys. (2 marks)

    (c) Name one alloy and state the metals it is made from. (1 mark)

    (5 marks)

    Marking scheme

    (a) An alloy is a mixture of two or more metals, or of a metal and a non-metal, made by melting and mixing them together while molten so that they combine. (b) Any two of: to increase hardness/strength; to improve resistance to corrosion/rusting; to lower the cost of the material; to improve appearance; to change/lower the melting point. (c) Any correct example, e.g. Bronze - made from copper and tin; OR Brass - made from copper and zinc; OR Steel - made from iron and carbon; OR Solder - made from tin and lead.

28. Question 28

    1 mark

    Brass, an alloy commonly used for making padlocks and musical instruments, is a mixture of which two metals?

    A. Copper and zinc

    B. Copper and tin

    C. Lead and tin

    D. Iron and carbon

    (1 mark)

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29. Question 29

    1 mark

    For rusting to occur, iron must be exposed to both

    A. water and oxygen

    B. heat and light

    C. water and nitrogen

    D. carbon dioxide and oxygen

    (1 mark)

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