Preventing rusting by galvanising
1 mark · EasyState one reason why coating iron with oil or grease helps prevent rusting.
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It acts as a barrier to air and water.
Also accept: it keeps out water and air; it prevents air and water reaching the iron
Common mistakes: oil reacts with iron; oil removes oxygen
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Marking points
B1 · 1 mark · States oil/grease prevents air and water reaching iron or acts as a barrier.
Worked solution
Coating iron with oil or grease works because it forms a barrier that keeps air and water away from the iron surface.