[momoho]

Is there any good references for this competition?
I want to answer the questions but many of them are not directly related to chemistry.e.g some of them are historical questions

[Big-Daddy]

You could have a look at the actual competition: http://www.c3l6.org/downloads (I am an alumnus ) There is no historical component, it's very good as an entry-level Olympiad though definitely easier than the other Olympiads (for one thing, it's a first round, and also, it's for one-year-younger students).

If you mean the Monthly challenge, yeah I wouldn't have a clue. It seems mostly like chemical general knowledge (mixed with quick research skills).