Which of the following hydrocarbonds has an acceptable huckel number but is not aromatic?

Options

A. [10]-annlene
B. [12]-annulene
C. [14]-annlene
D. [18]-annulene

Answer

A

Explanation

Although it has a huckel number the molecule connot adopt the essential planar conformation if all the double bonds are cis or one of the double bonds is trans, the angle strain is excessive. The isomer with two trans double bonds cannot be flat because two of the H atoms interfere with each other.