Well, see... there are a lot more sources for HSC papers than prelims because prelims are just not important enough.
Seriously though, get as many as you can from your teachers. If you can't find any, go through your textbooks and do end-of-chapter exercises.
Doing syllabus summaries can also be helpful.
I'll give you a question right now -
identify some combinations of solutions which will produce precipitates.
Too easy?
EDIT: Oh, and did you know that your name is the type of material that the thin window of Geiger-Müller tubes are made of?