Depends clearly on what you like. But from experience a few things to mention:
HSC Physics:
- The theory and concept by itself are not hard to understand. Although the HSC questions are not very straightforward. The questions tend to give scenarios or cases which relate to the concept, and you need to expand your thinking and be able to connect to various different situations where these concepts can be involved.
- Physics is not all mathematical. In year 12 the only maths dominated module is module 5 (Advanced Mechanics), even so you need to be able to grasp hold of the theories and concepts particularly.
- Some parts of physics require memorisation of history (specially module 7 Nature of light). Nature of light is quite literally a history lecture, in terms of how theories on light were investigated and found out.
- At times certain concepts and ideas do not make sense, and you need to do research outside of the syllabus in order to understand the theory well, and read/revisit certain topics multiple times to understand it.
- Overall, each module has its certain pros and cons. It is definitely not easy, and I'd probably say it is harder than chemistry because of some theories and concepts. But in saying that, its not that much harder than chemistry either. It really depends on you.
HSC Chemistry:
- The theories and concepts are very straightforward. Application of these are also straightforward. Unlike physics, the scenarios given are much more easier and straightforward, so if you know your content well its not that hard.
- Module 5 is mathematical, and includes quite a few hard maths question, in terms of equilibrium constant and solubility constant measurements. If you like maths, this is a plus point.
- Chemistry has more memorisation than physics, as its more broad. Each module, requires some extent of memorisation. If you do not like memorising lots of concepts and rules, then chemistry will definitely be a bit challenging.
- Chemistry experiments and physics experiments are pretty similar. (Not much difference except that physics experiments are boring but thats a personal opinion).
- Chemistry is content heavy (very content heavy) and this probably the main reason why it scales better than physics. There is a lot of content to cover, and memorisation isn't the way out, you need to be able to understand the reasoning behind each concept.
- Overall its hard because of the amount of content and memorisation. But if you know your content well than, its not that hard.
Again depends on you strengths. But from personal experience physics theories and concepts are a bit harder to understand than chemistry. Also, the mathematical aspects are not that hard in physics as people may exaggerate it to be.
If you study well from the start of year 11, then they both should be pretty straightforward.