4. Alkanes and Cycloalkanes

Which of the following is not a conformer of $\mathrm{butane}$?

Which conformer of ${\mathrm{tert}}^{-}-\mathrm{butylcyclohexanol}$ is the most stable at room temperature?

Given the Newman projection of $2_3$,$3_{\mathrm{dimethylbutane}}$ looking down the $C_2–C_3$ bond, where both methyl groups are gauche to each other, estimate the strain energy of this conformation.

Which of the following statements about the conformations of acyclic alkanes is true?

Which chair conformation of $1_{\mathrm{tert}-\mathrm{butyl}}-4-\mathrm{methylcyclohexane}$ has the lowest energy?

Which of the following conformers of $C_2{H}_6$ (ethane) has the highest energy?

Which of the following represents a gauche conformer of $C_2{H}_6$ (ethane) or $C_2{H}_5{F}_2$ (2-fluoroethanol)?

Which of the following best describes the process of translating a theoretical conformer of ethane from the staggered to the eclipsed conformation?

In 2-butanol, which group is gauche to the hydroxyl ($\mathrm{OH}$) group in its most stable staggered conformation?

Given the following conformations of 2-methylbutane: (A) anti (methyl and ethyl groups opposite), (B) gauche (methyl and ethyl groups $60°$ apart), (C) eclipsed (methyl and ethyl groups aligned), and (D) fully eclipsed (methyl and methyl groups aligned), rank them from lowest to highest energy.

Determine if the following pairof molecules is isomers or conformers?

In the lowest energy conformation of $C_2{H}_6$ (ethane), what is the dihedral angle between the two methyl groups?

Determine if the following pair of molecules isisomers or conformers?

Given the conformations of ethane: staggered, eclipsed, and gauche, rank them in order of increasing energy.