Hi Kylie,
I am in the same boat as you! I am getting ready for my 8th grade exams at the end of this year along with my VCE Music Performance Units 2 exam.
The best tip I have received for identifying the chords, whether they are in root, first inversion or second inversion, is to listen for the top note (easier to listen for) and then sing down, like an arpeggio until you hear it 'resolve' to the root note. It sounds weird, but I used to have so much trouble with this until my VCE Music teacher taught me this methodl. Obviously, as you get better, you will eliminate any actual singing and just do it in your head. When you are singing down, you should be able to count the notes you need to go until it resolves to the root. Play various chords on the piano in your vocal range and try...start off knowing what the inversion is so you understand this concept. Don't forget you also have to identify the diminished root chord as well in the exams.
By the way, what pieces are you doing?