[w451208]

Would these not be enantiomers if you rotated the second molecule 180 degrees?



Also why would these not be identical?



Wouldnt these be diastereomers?



How are these identical? The ring flip would cause a change in position.

[jake.n]

40)  This is a single compound.  You can see this by rotating either structure by 180°.

42)  This looks to me like a single compound

47)  Try imagining (I) from the other side of the viewing plane.  Does it look like (II).  It's tempting to assume that since both dashes/wedges changed that these are diastereomers, but in fact you are just changing you viewing angle. 

55)  This is a monosubstituted ring, and any way you draw 1-bromocyclohexane it will always be the same compound, because it is achiral.  Also, ring flips are a conformational change and only alter the equitorial-axial position of substitutents and does not change the absolute stereochemistry.

These kinds of questions are much easier to answer with models.