3-42 Consider 2-methylbutane (isopentane), Sighting along the C2C3 bond: a. Draw a Newman projection of the most stable conformation. b. Draw a Newman projection of the least stable conformation. c. If a CH3CH3 eclipsing interaction costs 11kJ/mol(2.5kcal/mol) and a CH3CH3 gauche interaction costs 3.8kJ/mol(0.9kcal/mol), make a quantitative plot of energy versus rotation about the C2C3 bond. 3.43 What are the relative energies of the three possible staggered conformations around the C2 - C3 bond in 2,3-dimethylbutane? (See Problem 3-42.) 3-47 Draw the most stable conformation of 1,4-dichlorobutane, using wedges and dashes to represent bonds coming out of the paper and going behind the paper, respectively