thats interestingif u really cant decide do sci adv. and then do chem and psyc as your some of your units in first year, decide on what u like best at the end of the year and then base your major on one of them. This is what i did/am doing and its definitly the best desicion i could have made.
Don't base your choice on the potential for a career as we learnt in psyc that this will lead to you enjoying your course less as your motivation will not be for enjoyment but for external reasons.