Q.Among the possible conformations of ethane, the most stable form is _______.

Both statements are true, and the small rotational energy barrier ($\approx 12.5\ kJ/mol$) is exactly why the two conformations cannot be separated — free rotation around the C–C single bond interconverts them almost instantly at room temperature.

Assertion: Ethane's staggered and eclipsed conformations (arising from rotation about the C–C single bond) cannot be physically separated/isolated as distinct compounds — this is true.

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Among ethane's infinite conformations obtained by rotation about the C–C single bond, the staggered form is the most stable because it has the least torsional strain.

Ethane (CH3–CH3) can rotate freely about its C–C sigma bond, giving different conformations. In the staggered conformation, the C–H bonds of one carbon are positioned exactly between (at 60° to) the C–H bonds of the other carbon (dihedral angle = 60°). This arrangement keeps the bonding electron pairs of the two carbons as far apart as possible, minimising electron-electron (torsional) repulsion.

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