British A-Level Chemistry: AS
The British university entrance exam system is called "A-Level" (Advanced level), and it is used in many countries.

A-Level courses courses usually last two years. Half way through the course, a series of "AS" exams are taken. At the end there are the more difficult "A2" exams.

Confusingly, there are four boards offering chemistry A-Level, and they irritatingly differ in detail. The four boards are:
AQA
OCR
Edexcel
WJCE