Thanks!
Would it be correct if I said for the definition of chiral centre
An atom that has four different groups bonded to it and the structures are mirror images of each other eg tartaric acid
The structures don't have to have mirror images, because it doesn't make sense with chiral centres. If a molecule has two chiral centres, you have 4 different stereoisomers: (R,R), (R,S), (S,R), and (S,S). Let's say you have the (R,S) molecule - its mirror image (or its enantiomer, see below for that correction) is (S,R). But in this case, there's two whole stereoisomers you've forgotten about - (R,R) and (S,S). This is actually true for the example you've given - tartaric acid has two chiral centres. I'd instead just stop at a chiral centre being a centre with four different groups attached to it (for interest: this doesn't even need to be a carbon molecule, out could be a nitrogen for example, but I feel that's beyond the scope of VCE. It's not even that complicated, but if the idea confuses you, just ignore it)
And for the definition of enantiomer - chiral molecules that are mirror images of one another . The molecules cannot be placed on top of one another and give the same molecule eg d- alanine and l-alanine
By "mirror images of each other", I'm assuming you mean the two molecules of differing chirality, not the molecule with itself? In which case, enantiomers definition is spot on in the first sentence only. The second sentence is a bit wrong in that you claim they're "the same molecule". If they were the same molecule, they'd have the same chirality. Some textbooks make it sound like molecules of differing chirality are the same, but they're not, or they wouldn't have different names. They can have the same functional groups, behave the same way in an achiral environment, and have the same connectivity - but their spatial arrangement is entirely different. Stick with just the first sentence, that's a perfect definition
If my definition of micelle was
A cluster of molecules that are found in certain solutions. A micelle forms due to the amphiphatic nature of fatty acids.
Would it be correct
You're half correct - you would HAVE to mention that the cluster is spherical formed with the lipophilic part of the molecule pointing onwards, and the hydrophilic part pointed towards to make a sphere. There are lots of supramolecular structures that your definition fits, including lipid bilayers, liposomes, vesicles, etc. I'm not sure how much of this is in the scope of VCE, BUT I couldn't find mention of even micelles in the study design, so this question may be redundant. All I know is that I, personally, would not accept that definition unless you at least also mentioned the shape of the cluster, because a cluster could be anything