The following table reports the molecular mechanics (MM) energy of four conformations of n-hexane, identified by trans ( t) or gauche (g) conformation about the central CC bonds. i) Briefly explain which term(s) in the general MM expression are most important for determining the relative energy of these isomers. ii) Using a series of suitable sketches, explain how multiple cosine functions can be combined to model the conformational behaviour of the central C-C bonds. iii) Use the data in th trans- or gauche-forms of a single CC bond. iv) Suggest a possible reason why the all gauche-form of n-hexane (g,g,g) has higher energy than would be expected from your answer to part iii)