What this tests
Syllabus point 9.5 — Corrosion of metals, in Metals. Difficulty medium (estimated from the question's demands, not a Cambridge rating).
Also set in
The same question, as Cambridge printed it in other papers.
Cambridge IGCSE Chemistry 0620 · 9.5 Corrosion of metals
November 2011 · Paper 12 · Question 10
One real Cambridge question from Metals, with the official answer. Cambridge has printed this question 7 times.