Grade 9 · CAPS

Grade 9 Corrosion

Natural Sciences and Technology practice questions with answers

Grade 9 Corrosion is part of the CAPS Natural Sciences and Technology curriculum, covering what corrosion is, how rust forms when iron reacts with oxygen and moisture, and how corrosion can be prevented. Learners practise describing the appearance and chemical formula of rust, naming the substances involved, and explaining protective methods such as painting, galvanising and electroplating. The practice questions below are drawn from ReClass's own question bank, based on real Grade 9 CAPS assessments, so learners can check their understanding of corrosion against the kind of questions used in an actual test.

Worked example

What term describes what happens when a metal rusts?

Answer & explanation

Corrosion

You'll also practise

  • 2.4 The name of the process where the exposed surface of a metal reacts with oxygen
  • Choose an item from COLUMN B that matches a statement in COLUMN A. Write only the letter (A – I) next to the question numbers (3.1 to 3.6) in the space provided: 3.2 The process that weakens a metal
  • Describe what rust looks like.
  • Painted iron furniture, left outdoors and exposed to air and rain for a long time, shows no signs of rusting. Explain how this is possible.
  • Give the correct term: to cover steel or iron with a more reactive metal, such as zinc, to protect it from rusting.
  • Give the correct term: the substance that dissolves or eats away at metals and other strong materials.
  • Rusting is a form of corrosion. What is corrosion?
  • Cars in a scrapyard change colour to brown after being neglected for many years due to prolonged exposure to water. What caused this deterioration?
  • Besides iron, name the other TWO substances involved in the process of rusting.
  • Give the chemical formula for rust.
  • Name the process that takes place when iron reacts with oxygen in the presence of moisture.
  • Give the common name given to the reddish-brown powder that forms when iron reacts with oxygen in the presence of moisture.
  • Suggest THREE ways in which rusting can be prevented.
  • List any TWO ways in which the formation of rust can be prevented.

Common mistakes

  • Thinking rust forms from oxygen alone, without needing moisture too.
  • Confusing corrosion (a slow, ongoing process) with combustion (a rapid reaction).
  • Naming only one way to prevent rusting when a question asks for more than one.

Aligned to CAPS Grade 9 Natural Sciences and Technology — Corrosion.

Check your own understanding

Start a personalised Grade 9 Corrosion practice session on ReClass.

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