Question -
Answer -
Due to the presence of asp3-hybridized carbon, the system is not
planar. It does contain six n-electrons but the system is not fully conjugatedsince all the six n-electrons do not form a single cyclic electron cloud whichsurrounds all the atoms of the ring. Therefore, it is not an aromatic compound.
(ii)
Due to the presence of a sp3 -carbon, the system is not planar. Further,itcontains only four n-electrons, therefore, the system is not aromatic becauseit does not contain planar cyclic cloud having (4n + 2) n-electrons.
(iii)
Cyclo-octatetraene is not planar but is tub shaped. It is, therefore, anon-planar system having 8 n-electrons.
Therefore, the molecule is not aromatic since it does not contain a planarcyclic cloud having (4n + 2) n-electrons.