An old steel key is kept in a sealed museum display case. The case contains air and a drying agent. The key does not rust. Why not?
The drying agent absorbs the oxygen that is needed for rusting
The sealed case stops the air moving around the steel key
The drying agent removes the water vapour needed for rusting
The steel key can rust only when it is completely under water
118 exam-style questions on AQA GCSE Chemistry 10.3 Using materials, covering 10.3.1 Corrosion and its prevention, 10.3.2 Alloys as useful materials, and 10.3.3 Ceramics, polymers and composites. Each one has a worked solution and a mark scheme showing where the marks go.