Would you be able to explain NMR coupling strength between axial and equatorial hydrogens once more? How do you know which hydrogens will couple? (Axial H with an axial H at the adjacent carbon will couple the strongest, because the dihedral angle is 180o. Axial and equatorial hydrogens or equatorial and equatorial hydrogens also couple, but much weaker, because of the less favorable dihedral angle. - GS).   Thanks.

Would you be able to explain what a meso-form is? Is it just an achiral molecule? (Almost. It is an achiral molecule with chiral centers - GS). Thanks.