1. When is a resonance hybrid needed to adequately depict bonding in a molecule? Using NO2 as an example, explain how a resonance hybrid is consistent with the actual bond length, bond strength and bond order of NO2. (4 marks) 2. Draw a Lewis structure for a resonance form of AsO43- and C102 with the lowest possible formal charges. Show the charges and give oxidation numbers of the atoms. (6 marks) 3. Identify the hybrid orbital used by the central atom(s) and the type(s) of bonds formed in (a) N3; (b) C3H4 (c) SO2 (6 marks) 4. Use MO diagrams to rank B2-, B2 and B2 in order of decreasing bond energy and decreasing bond length. (4 marks)