I can't really give advice to economics since I didn't do the subject, but I did Chemistry (albeit didn't try as hard for it I already got Band 6 in software), but I still have tips from experience.
For Chemistry, as
@Greninja340 said, yes the content itself is rather easy to learn/straightforward. However, the questions in exams can be pretty hard because they aren't as straightforward anymore. Last year's HSC Chemistry was pretty testament to this, focusing on how students can
adapt and interpret the question to draw logical, scientific conclusions when given any problem as opposed to just familiar scenarios. (The last question and the Calcium Hydroxide question were stood out to me as the most difficult, but I managed to solve it regardless).
My advice for Chemistry is to please go back and relearn a lot of the fundamental concepts that you might've glossed over in Year 11. The Year 12 Chemistry content builds off of the core things you learned in Year 11. Having a really good understanding of Year 11 stuff can easily transition into faster learning of content in Year 12. Trust me, without it, Year 12 Chemistry becomes a lot harder to learn. In addition to Module 2 stuff, (esp limiting reagents, stoichiometric ratios), go back and learn about stuff like 'electronegativity' and the relative strengths between the different types of bonds (both intra- and intermolecular), as it can really help with Module 7.
Be sure also to establish connections between modules. Band 6 Science students will often ask "why" something is done/or why something happens rather than just accepting it. For example, you will later learn about Esterification in Module 7. You'll learn that reflux condenser is needed for the process to occur in a lab. But why? Well, it's because the normal esterification process is actually within chemical equilibrium that is favoured to the side of the reactants, not the product (the ester). So, the rate of reaction needs to be increased, and sufficient energy needs to be introduced into the system to overcome the activation energy for the process to occur, so equilibrium can proceed to the right. That is why the system must be heated. But in that process, you remember that alcohol (one of the reactants), has a low boiling point, so the condenser is needed to stop it from vaporising and to not waste any alcohol. Whilst I did go into a lot of content, what was important was the
connections I established. As you can see, I used concepts from Module 5 and connected it to a single process in Module 7. Understanding as opposed to just accepting/memorising is important in scoring high marks in the HSC, and it really helps you remember the content a lot easier.
And finally, (this is not surprising), but Chemistry requires a decent amount of logic/problem-solving. The HSC Chemistry exams have questions designed for students in unfamiliar situations. Sometimes, while a question might seem hard, my tip is to (quite literally) imagine yourself or imagine the process taking place. I used this for the final question on the 2020 HSC exam, and from then on, it was easy. I just thought about how the NaOH must react first and it needs to undergo dissociation, however, there are more moles of NaOH than HCl, so HCl is limit reagent, and hence, less moles will react to release energy. The total energy released is responsible for temperature, so it's obvious to add them and then solve for the final temperature.
I hope that these tips are useful and can really help with your HSC!! Just remember, consistent studying/good understanding will pay off.
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