Question

Staggered and eclipsed conformers of ethane are :

• A. Rotamers
• B. Mirror images
• C. Enantiomers
• D. Polymers

Hint:

Conformers that can be interconverted by rotation around single bonds are called rotamers. For ethane, the staggered conformer is more stable than the eclipsed conformer due to lower torsional strain.

Answer 1

The Correct Option is A

Conformational isomers, or conformers, are stereoisomers that can be converted into one another by rotation about a single bond.
The term "rotamers" is a specific name for these conformational isomers.
In ethane ($CH_3-CH_3$), rotation around the central carbon-carbon single bond leads to different spatial arrangements of the hydrogen atoms.
The two extreme arrangements are the staggered conformation (where hydrogens on the front carbon are positioned between the hydrogens on the back carbon, most stable) and the eclipsed conformation (where hydrogens on the front carbon are directly in front of the hydrogens on the back carbon, least stable).
These staggered and eclipsed forms are interconvertible by rotation and are therefore called rotamers.
Options (B) and (C) are incorrect because they are not mirror images of each other. Option (D) is incorrect as polymers are large molecules made of repeating monomer units.