Do you honestly think they would make Year 12 easier then Year 11?
The whole point of Year 11 is to gear up for Year 12
So it's safe to assume Year 12 increases your workload.
A LOT
Also, do not be worried about the mark you get in your test
The only thing you should worry about is rank
The teachers NEED to make it really hard. Otherwise, too many people would get 100% and the-like, making it impossible to seperate the top students
My teacher once told me, "We hate it when students get 100%. It defeats the purpose of testing to see the rank. What if three students get 100% but one student is twice as smart as the other two? They end up with the same rank. That's why we make the tests so hard"
Besides, the harder it is, the more mistakes you make, the more you can go back to it and learn it
It's better to head into the HSC with all the hard stuff learnt rather then to know all the easy stuff but not the hard stuff =)