Not Keltingmeith, but I do know a few of these answers, so I’ll answer as much as I can. (I moderate a lot of the Victorian careers stuff for AN. Hope you don’t mind me answering.)
1. If I were to get into the course, what would I major in? For example, I have to major in Chemical Systems to get into Chemical Engineering, and if I change my mind, would that limit my options of doing a graduate degree in another course.
Depends on the units (uni talk for subjects) you’ve taken at uni and what you want to apply for. Some of the other postgrad courses related to chemistry e.g.
Master of Industrial Research (Chemistry) at UoM, would likely still accept you, both at UoM or elsewhere. You’d still qualify for a bunch of relatively unrelated courses e.g. postgrad med (although I know you’re not after that, it’s purely there as an example), as long as you take a few prerequisite biology units during your undergraduate degree i.e. the Bachelor of Science in this case, and fulfil all the entry criteria.
2. I don't really understand postgraduate courses. Will you be able to explain how it would relate to me?
Postgraduate courses are the courses you do after an undergraduate course. So for you it’d be something like this: VCE —> Bachelor of Science (maybe) —> Master of Engineering (Chemical Engineering). You don’t have to do the postgrad course at the same institute as your undergrad course (e.g. you could go to La Trobe for your postgrad course after doing your Bachelor of Science at Melbourne). The courses at postgrad level usually are stuff like Masters, Graduate Diploma, Advanced Diploma or PhD. I’ll let Keltingmeith explain a bit more seeing as they actually take a postgrad course (PhD).
3. If I don't end up becoming a chemical engineer, what can I do with the Bachelor of Science degree? what other pathway options do I have?
As a lot of people have said above, there’s plenty of chemistry and science jobs out there. As pointed out above, one career path for chemistry grads is in QA (quality assurance) in various industries (think water, cosmetics, food, medication, etc.). Here’s a couple of non-exhaustive lists (
here and
here).
The list of other options is pretty wide. I’d suggest doing some research, because only you’ll know what suits you best and interests you the most.
4. If Melbourne does not accept me, can I complete a Bachelor of Science at another university, for example La Trobe, and do a graduate engineering degree at Melbourne or Monash?
According to
this, possibly, if you do a chemistry/ chemical engineering major through another course.
5. If I were to do a double degree, for example Bachelor of Commerce/Bachelor of Science at La Trobe University, what would this entail?
You’d study commerce and science units, taking around 4 years assuming you study full time. You’d pick a major in commerce and another major in science. It’s not too different to how you’d study if you were doing these as single degrees, just that you’re studying units from different areas at the same time.
Would this keep my options open?
You’d be able to have careers in science and/ or commerce, depending on your choice. The only difference you’d have is that you would’ve taken less units in either area compared to someone with a single degree.
How much work and effort would be expected? Will it be helpful?
Work and effort: not much different to each of these as single degrees, except you’re doing it for 4 years.
Helpfulness: Depends on your idea of helpfulness. Workforce-wise it’ll help to diversify, but mean that you’ll have slightly less in depth knowledge in either area. Helps to cover more areas too, but also means less room for changing majors/ minors (specialities) as you go along, because you have less units, unless you transfer.
What is the atar required to get into this course at Monash or La Trobe (like an approximation)?
Bachelor of Commerce/ Science at Monash: link
here - lowest selection rank (including adjustments) is 92 (86 if you qualify for Monash Guarantee)
Bachelor of Commerce/ Science at La Trobe: link
here - lowest selection rank (including adjustments) is 82.60.
These are this year’s stats for students who states first year in 2020. In past years, it’s hovered around the early 90s (after adjustments) for Monash and early 80s (after adjustments) for La Trobe. Without adjustments, you’re looking at around high 80s to be relatively safe for Monash and around the mid/high 70s for La Trobe. (Adjustments are different per person and takes into account special consideration, which has to do with personal disadvantage and equity.)