What this tests
Syllabus point 4.1 — Electrolysis, in Electrochemistry. Difficulty easy (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 · 4.1 Electrolysis
November 2017 · Paper 23 · Question 9
One real Cambridge question from Electrochemistry, with the official answer. Cambridge has printed this question 3 times.