please help with a,b and d

(a) Using the ligand field approach, show how the octahedral crystal field splitting parameter, 0, is affected when pure -donor ligands are replaced by acceptor ligands. Fully label your diagram. (8) (b) How does the observation in (a) above rationalise one of the anomalies of the spectrochemical series? (3) (c) Find organic fragments isolobal with the following: (i) [Fe(CO)4] (4) (ii) [Co(NH3)5]2+ (4) (d) You are given a mixture containing lantharide cations Pr (III), Tb (III), Nd (III) and Ce (III). Briefly outline an approach you would use to separate them. (6)