Free Corrosion questions for IGCSE Chemistry (0620), part of Metals. Each question has the answer and the marking points an examiner would look for.
Generate a full Corrosion worksheet →All Metals questionsIron can be protected from rusting.
1 A scratched layer of tin still protects iron from rusting.
2 Zinc protects iron because zinc is more reactive than iron.
3 Attaching a block of copper to an iron ship gives sacrificial protection.
Which statements are correct?
Answer: D
Which term is described by this statement?
“The corrosion of iron or steel, which requires both oxygen and water.”
Answer: C
Rust is hydrated iron(III) oxide.
Write a word equation for the formation of rust.
Explain why salt water speeds up rusting.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | iron + oxygen + water → hydrated iron(III) oxide iron + oxygen + water → hydrated iron(III) oxide B1 | 1 |
| (b) | electrolyte, faster the dissolved salt makes the water a better conductor (electrolyte), increasing the rate of corrosion B1 | 1 |
Ships are protected from rusting by blocks of zinc or magnesium attached to the hull.
Explain how these blocks protect the iron.
Explain why the blocks must be replaced from time to time.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | more reactive, corrode instead zinc/magnesium are more reactive than iron B1 they are oxidised/corrode instead (sacrificial protection) B1 | 2 |
| (b) | they corrode away they are used up as they corrode B1 | 1 |
Iron rusts when exposed to the environment.
State the two substances needed for iron to rust.
Describe an experiment to show that both are needed.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | water and oxygen water B1 oxygen B1 | 2 |
| (b) | three tubes: water+air; dry air (calcium chloride); boiled water + oil tube 1: iron nail in water and air (rusts) B1 tube 2: dry air with anhydrous calcium chloride (no rust) B1 tube 3: boiled water with a layer of oil (no rust) B1 | 3 |
Galvanising and sacrificial protection prevent rusting.
Describe galvanising.
Explain why galvanised iron does not rust even when the zinc coating is scratched.
Give one barrier method of preventing rusting.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | coating with zinc coating iron/steel with a layer of zinc B1 | 1 |
| (b) | zinc more reactive, oxidises instead zinc is more reactive than iron B1 it is oxidised/loses electrons instead of the iron (sacrificial protection) B1 | 2 |
| (c) | paint / grease / plastic coating painting, greasing or coating with plastic B1 | 1 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in