To solve this problem, we need to understand the concept of conformers in ethane.$\\$Conformers are different spatial arrangements of a molecule that can be interconverted by rotation around$\\$single bonds. In ethane, the rotation occurs around the carbon-carbon single bond. The most common$\\$conformers of ethane are the staggered and eclipsed conformations.$\\$Key points to consider:$\\$• In conformational isomerism, the bond lengths and bond angles within the molecule remain unchanged.$\\$• The rotation around the C-C bond does not affect the bond lengths or bond angles; it only changes the$\\$relative positions of the hydrogen atoms attached to the carbon atoms.$\\$Given the options:$\\$Option 1: Bond angle changes but bond length remains same$\\$Option 2: Both bond angle and bond length change$\\$Option 3: Both bond angles and bond length remain same$\\$Option 4: Bond angle remains same but bond length changes$\\$Analysis:$\\$• Option 1 is incorrect because the bond angles do not change during rotation.$\\$• Option 2 is incorrect because neither bond angles nor bond lengths change during rotation.$\\$• Option 3 is correct because both bond angles and bond lengths remain the same during rotation.$\\$• Option 4 is incorrect because bond lengths do not change during rotation.$\\$Therefore, the correct statement is:$\\$Option 3: Both bond angles and bond length remain same.$\\$This corresponds to the correct understanding of conformational isomerism in ethane.