Which of the structures below would be aromatic?
A)I and IV
B)I, III, and IV
C)III and IV
D)II

Question

Which of the structures below would be aromatic? 
A)I and IV 
B)I, III, and IV 
C)III and IV 
D)II

Quizplus · Accepted Answer

For a molecule to be aromatic, it must fulfill the following criteria:
1. The molecule must be cyclic.
2. The molecule must be planar.
3. The molecule must have a conjugated system of pi electrons that follows Hückel's rule (4n+2 pi electrons, where n is any non-negative integer).
 
In this case, only structures III and IV qualify as aromatic since they are cyclic, planar, and have a conjugated system of 4n+2 pi electrons. Structures I and II are not cyclic, and structure II does not have 4n+2 pi electrons.

Which of the Structures Below Would Be Aromatic