Question 1 Medium
Which two elements are in bronze?
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Answer: copper and tin
- Bronze is a copper alloy.
- It is mixed with tin.
Corrosion, alloys and materials: GCSE Combined Science Chemistry practice questions
A second set of questions on corrosion, alloys and materials. They are different from the ones on the topic page. Try each, then open the answer and compare your working.
More questions
Question 2 Medium
Why does aluminium not corrode quickly even though it is reactive? A thin layer of what forms on its surface?
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Answer: aluminium oxide
- Aluminium reacts with oxygen in the air.
- It forms a thin layer of aluminium oxide that protects it.
Question 3 Hard
What percentage of 18 carat gold is pure gold?
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Answer: 75%
- 24 carat is pure gold.
- 18 ÷ 24 × 100 = 75%.
Question 4 Hard
A ring of mass 20 g is 18 carat gold. What mass of gold does it contain? Give your answer in g.
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Answer: 15 g
- 18 carat gold is 75% gold.
- 0.75 × 20 = 15 g.
Question 5 Hard
Why do the atoms of a different element in an alloy make it harder? They are a different …
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Answer: size
- Different-sized atoms distort the layers.
- The layers cannot slide easily.
Question 6 Hard
A block of magnesium is attached to an iron pipe. Is magnesium more or less reactive than iron?
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Answer: more reactive
- Magnesium is above iron in the reactivity series.
- So it is more reactive and corrodes first.
Question 7 Hard
Which method of rust protection still works when the surface is scratched: painting or galvanising?
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Answer: galvanising
- Painting is only a barrier.
- Galvanising also gives sacrificial protection.
Question 8 Hard
Iron nails are left in four test tubes. Which one rusts fastest: dry air, boiled water with oil on top, water with air, or salt water with air?
Show answer
Answer: salt water with air
- Rusting needs oxygen and water.
- Salt speeds it up, so salt water with air rusts fastest.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
What is corrosion?
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The destruction of a metal by reaction with substances in the environment.
Check 2
What is rust?
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Hydrated iron(III) oxide.
Check 3
What two substances are needed for rusting?
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Oxygen and water.
Check 4
Is rusting oxidation or reduction?
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Oxidation, because the iron gains oxygen.
Check 5
What is the word equation for rusting?
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Iron + oxygen + water → hydrated iron(III) oxide.
Check 6
Name three barrier methods of preventing rust.
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Painting, oiling or greasing, and coating with plastic or another metal.
Check 7
What is sacrificial protection?
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Attaching a more reactive metal that corrodes instead of the iron.
Check 8
Name two metals used for sacrificial protection.
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Zinc and magnesium.
Check 9
What is galvanising?
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Coating iron or steel with zinc.
Check 10
Why does galvanised steel not rust when scratched?
Show answer
Zinc is more reactive than iron, so it corrodes first.
Check 11
Why does aluminium not corrode quickly?
Show answer
A thin layer of aluminium oxide forms on its surface and protects it.
Check 12
Why is gold resistant to oxidation?
Show answer
It is very low in the reactivity series, so it hardly reacts with oxygen.
Check 13
What is an alloy?
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A mixture of a metal with at least one other element.
Check 14
Why is an alloy harder than a pure metal?
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The different-sized atoms distort the layers, so the layers cannot slide easily.
Check 15
What is steel?
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An alloy of iron with a small amount of carbon.
Check 16
What is brass made of?
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Copper and zinc.
Check 17
What is bronze made of?
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Copper and tin.
Check 18
What does stainless steel contain?
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Iron with chromium and nickel. It does not rust.
Check 19
What does 24 carat gold mean?
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Pure gold.
Check 20
What percentage of 18 carat gold is gold?
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75%.
Check 21
Describe the typical properties of metals.
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Shiny, high melting points, high density, good conductors of heat and electricity, malleable.
Check 22
Why can pure metals be bent and shaped?
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The layers of atoms can slide over each other.
Check 23
What is a composite? (Separate Chemistry only)
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A reinforcement such as fibres embedded in a matrix or binder.
Check 24
What is a ceramic? (Separate Chemistry only)
Show answer
A hard, brittle, non-conducting material such as glass or pottery.
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