Talk to someone when you enrol (if you havent already, if you have call up the faculty to organise a time to come talk to someone). I can't say whether it will be fine or not but go see.
I think you're a bit confused about what you need to fit in. See
http://www.sci.monash.edu.au/undergrad/progamstudy/pleorthree.html You need to have a maths subject out of whatever's listed, and then go for option 1. It's simply picking 3 sequences so people don't go mental and do one of everything and then realise they don't actually meet prereqs for any 2nd year unit. Don't worry about that physical earth life science crap. You just need to essentially choose 3 subjects, and make sure you meet the maths requirement as well
(doing MTH1020 in 1st and then MTH1030 in 2nd semester will cover the maths requirement)
You can even do something like this and it meets all your requirements:
Sem 1
MTH1020
ATM1010
other science sequence (ie ASP1011 I am not plugging anything)
random arts unit
Sem 2
MTH1030
ATM1020
other science sequence (ie ASP1022 I am still not plugging, it is merely alphabetically first)
random arts (or other faculty even

) unit
I hope some of this has made sense
If you want to reach me quicker, msn/email
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