Polyacetylene was one of the first conducting polymers to be isolated a. In the molecular theory of conductance for organic molecules explain the meaning of the terms HOMO and LUMO and contrast them with the equivalent band structure model for conduction in inorganic semiconductors. (8 marks) b. Sketch a few repeat units of a polyacetylene polymer chain indicating the type and sequence of the C-C bonds. (2 marks) Pure polyacetylene is an electrical insulator. Explain why this was originally unexpected given the C-C bonding along the carbon chain and discuss the proposed mechanism for the high electrical resistivity. (6 marks) d. Doped polyacetylene conducts electricity through the presence of defects. Sketch the nature of a neutral soliton defect in terms of the local change in atomic bonding and how it changes the molecular orbital energy diagram. (4 marks)