Which of the following best describes the difference between $\mathrm{cis}$ and $\mathrm{trans}$ conformations in cyclohexane rings?

• A. $\mathrm{cis}$ and $\mathrm{trans}$ conformations refer to the rotation around a single bond in an open-chain alkane.
• B. $\mathrm{cis}$ and $\mathrm{trans}$ conformations are only possible in aromatic rings, not in cyclohexane.
• C. In the $\mathrm{cis}$ conformation, both substituents are always axial, while in the $\mathrm{trans}$ conformation, both are always equatorial.
• D. In the $\mathrm{cis}$ conformation, two substituents are on the same side of the ring plane, while in the $\mathrm{trans}$ conformation, they are on opposite sides.

Answer: (D)

Verified step by step guidance

1. Understand that in cyclohexane rings, the terms \(cis\) and \(trans\) describe the relative positions of substituents attached to the ring carbons.
2. Recall that cyclohexane adopts a chair conformation, which can be thought of as a three-dimensional ring with a defined 'plane' for reference.
3. In the \(cis\) conformation, both substituents are located on the same side of the ring plane, meaning both are either above or below the plane.
4. In the \(trans\) conformation, the substituents are on opposite sides of the ring plane, so one is above and the other is below the plane.
5. Note that \(cis\) and \(trans\) in cyclohexane are not about rotation around single bonds (as in open-chain alkanes), but about the spatial arrangement of substituents relative to the ring plane.