1. (a)  Reacting Pt²⁺ with two equivalents of each of the ligands NO₂^- and en, it is possible to prepare several complexes that could be described as both geometric and  optical isomers of each other.  Explain.

       (b)  What other type of isomerism might one envisage arising from the reaction given in (a)?
 
2.  The aquated Cr²⁺  ion is sky blue in colour.   If you were to obtain  its UV-VIS spectrum, in what wavelength range will you expect this complex to absorb?   Explain your reasoning. 
 
3.  (a)  Determine the crystal field stabilization energy (CFSE) for the high and low spin complexes of an octahedral Co²⁺ metal complex. Make sure to include with your answer the energy for electron pairing as well. 

       (b)  Identify which spin state is preferred based solely on the CFSE's.   
       (c)  Explain why though there is a preference for one over the other both cases are still possible.