Actually, good point - I'll leave some tips here for anyone who wants to do the chem NQE.
Chem NQE is two hours, and it tests quite a bit of stuff - I recommend learning your 1/2 course thoroughly and having a quick flick through the unit 3/4 course, just to get a good background reading. Recommend this site:
http://www.chemguide.co.uk - it has plenty of stuff here.
If you haven't looked at past papers, I recommend you do so.
http://www.asi.edu.au/nqe/pastpapers.phpThere are 15 multi choice qns worth 2 marks each, and three 30 mark extended response questions. I recommend you spend about half an hour per section, but spend a little less time on the multi-choice section. If you didn't finish the paper, don't worry, I didn't finish the paper last year when I did the NQE but I still got an invite to summer school. And you don't need to get anywhere near 100% to get into summer school; in year 10 I got an offer to go to summer school and I only answered about 40% of the paper! It was a difficult paper though. Generally I'd say about 60% (~70/120) would be a very rough estimate for the cutoff to get into summer school.
If you get into the top 24 in the country, you get an invite to summer school, where you learn heaps of stuff, equivalent to a first year chem course. It was a brilliant experience. Absolutely brilliant. The mentors are awesome. My classmates were awesome. You also work for about 4 hours in a lab every day, learning and doing some really cool stuff
For selection into the 4-person team, there is a 2-hour trial lab exam (which may count for 10% if you do really well), a final 4-hour lab exam, and 6 weeks after summer school finishes there are two 3-hour papers - the final selection exam. You also get medals for the final selection exam, depending on how you go. And if you make the team, there are another two training camps (1 week each) and then you go and compete in the International Chemistry Olympiad - next year it is in Washington DC, USA. When I went to the IChO in Ankara, Turkey this year, I can say one thing: it will be an experience I will never, ever forget. It was amazing, and even now I wish I was still with my friends from all over the world in Turkey.