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3. Answer ALL parts of this question. Answer all parts (i) - (iii) of this question. Br Br OH D Me D D B Me Br H H Me CI OH HH H Br Me H HHH OH F D E (i) Define the stereogenic centres for the molecules above as Ror S (8 marks) (ii) Draw Natta projections (zig-zag structures) for compounds E and F. Draw compound E as a Fischer Projection. (3 marks) (iii) Two of the compounds can racemise at high temperature. Identify them and comment on the mechanism of racemisation, (4 marks) (b) Answer BOTH parts of this question. (i) For the reaction below, draw all the products, and label the stereogenic centres as R or S. (5 marks) NaBHA ? MeOH (ii) How could you separate these products, through physical or chemical means? (5 marks) (c) Draw the lowest energy conformations of hydrazine (NH2-NH2) and ethane (CH3-CH3), explaining why the structures you draw have the lowest energies