Account for each of the following observations about pairs of substances. In your answers, use appropriate principles of chemical bonding and/or intermolecular forces. In each part, your answer must include references to both substances.

(a) K₂Se has a higher melting point than SeS₂. Explain this observation in terms of principles of chemical bonding. Include a particle-level view of the structure of each as a part of your explanation.

(b) Explain why SeI₆ has a higher melting point than SeO₂. Use Lewis structures and the intermolecular forces present with each in your explanation.

(c) Consider the methanol (CH₃OH) and ethanol (C₂H₅OH). Which would you expect to have a higher boiling point? Justify your prediction.

(d) Draw the complete Lewis structures for an ethanol molecule and a methanol molecule, showing how and where a hydrogen bond could form between them.

(e) The bond length between carbon and oxygen is greater in CO₃^2- than in CO₂