MeCN solutions of NbCl5 and HF contain a mixture of octahedral [NbF6] , [NbF5Cl], [NbF4Cl2] , [NbF3Cl3] and [NbF2Cl4] . Predict the number and coupling patterns of the signals in the 19F NMR spectrum of each separate component in this mixture, taking into account possible isomers. (Assume static structures and no coupling to 193Nb.)

On solidification from a melt, the polymer polyethylene forms a semi-crystalline spherulite structure. (i) sketch an individual spherulite and label the amorphous and crystalline regions. (ii) draw a schematic to show the changes in specific volume with temperature during cooling from the melt, comparing it to the theoretical extremes of fully crystalline and fully amorphous (indicate tm and tg)