The incorrect statement regarding conformations of ethane is:
Ethane has an infinite number of conformations
The dihedral angle in staggered conformation is
Eclipsed conformation is the most stable conformation
The conformations of ethane are inter-convertible to one another
Correct answer:C
Standard Method
Given: Statements about conformations of ethane.
Find: The incorrect statement.
Evaluate each statement using the stability of ethane conformations.
Ethane can rotate about the carbon-carbon sigma bond, so it has infinitely many conformations. This statement is correct.
The staggered form is commonly represented with a dihedral angle of
so this statement is treated as correct in the context of ethane conformations.
Eclipsed conformation is not the most stable conformation. The staggered conformation is more stable because it has minimum torsional strain.
Different conformations of ethane are inter-convertible by rotation about the carbon-carbon bond. This statement is correct.
Therefore, the incorrect statement is Option C.
Stability-Based Explanation
Given: Ethane shows conformations due to rotation around the carbon-carbon single bond.
Find: Which option states an incorrect fact.
Ethane has staggered and eclipsed limiting conformations, along with infinitely many intermediate conformations during bond rotation.
The eclipsed conformation is the least stable because adjacent C-H bond electron clouds repel each other more strongly. The staggered conformation is the most stable because this repulsion is minimized.
So the statement "Eclipsed conformation is the most stable conformation" is incorrect.
Hence, the correct option is C.
Confusing most stable with least stable. In ethane, eclipsed conformation has higher torsional strain, so it is less stable; use staggered as the most stable reference.
Treating only staggered and eclipsed forms as the only conformations. Ethane rotates continuously about the carbon-carbon bond, so there are infinitely many conformations, with staggered and eclipsed as important limiting cases.
Misreading the question and marking a correct statement instead of the incorrect one. First classify each option as correct or incorrect, then choose the statement that violates conformational stability.
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