The incorrect statement regarding conformations of ethane is :

The incorrect statement regarding conformations of ethane:

- Ethane has infinite number of conformations: Correct - rotation around the C-C bond gives continuous conformations.

- The dihedral angle in staggered conformation is 60°: Correct - the H atoms are 60° apart in staggered form.

- Eclipsed conformation is the most stable conformation: Incorrect - the staggered conformation is the most stable. The eclipsed is the least stable.

- The conformations of ethane are interconvertible: Correct - they freely interconvert by rotation.

The incorrect statement is Option (3).