What this tests
Syllabus point 2.3 — Isotopes, in Atoms, elements and compounds. Difficulty hard (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 · 2.3 Isotopes
June 2010 · Paper 13 · Question 2
One real Cambridge question from Atoms, elements and compounds, with the official answer. Cambridge has printed this question 3 times.