Understand the terms

Ethane, $\mathrm{C_2H_6}$, has a single bond between the two carbon atoms.

Because a $\mathrm{C-C}$ single bond allows free rotation, different spatial arrangements of the hydrogen atoms are possible.

Staggered and eclipsed forms

The two important conformations of ethane are:

• Staggered conformation
• Eclipsed conformation

These forms arise due to rotation about the $\mathrm{C-C}$ single bond.

What are such conformations called?

Conformations obtained by rotation around a single bond are called rotamers (or conformers).

Therefore, staggered and eclipsed conformers of ethane are rotamers.

Check options

• A: Polymers $\rightarrow$ Incorrect. These are large molecules made by repeating units.
• B: Rotamers $\rightarrow$ Correct.
• C: Enantiomers $\rightarrow$ Incorrect. Enantiomers are non-superimposable mirror images.
• D: Mirror images $\rightarrow$ Incorrect. Staggered and eclipsed forms are not mirror images; they are rotational conformations.

Final answer

$\boxed{\text{B: Rotamers}}$

Comparison with stored correct answer

Stored correct answer = B

Derived answer = B

Hence, the derived answer agrees with the stored correct answer.