CHEM 250 Midterm: Chem250-Midterm(Fall2013)-Answers.pdf
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Multiple choice answers: c, b, b, e, c, b, e, c, d, c, a, d, b, a, e, d, a, b, d, not graded. Part ii (10 marks: the visual pigment in animal cells consists of an isomer of retinal linked to the protein opsin, as shown below. Draw an alternative resonance form for this species that shows the positive charge situated on the starred carbon instead of the nitrogen atom and include the curved arrows to show the electron flow. One mark for arrows, one mark for correct structure. H3cnhproteinch3ch3*b) the structures below show the stepwise bond making and bond breaking in this reaction. Draw curved arrows on the diagram to show the electron flow that has occurred in each step. One mark for each step being correct: using the chair diagram below, draw the most stable chair conformation of trans-1-ethyl- One mark for equatorial: draw the correct structure for the molecule :
