Explain the following terms:
$(i)$ Alicyclic compound
$(ii)$ Heterocyclic compound
$(iii)$ Non-benzenoid compound

(N/A) $(i)$ Alicyclic compounds: These are cyclic organic compounds that contain carbon atoms arranged in a ring,but they do not possess aromatic character. They resemble aliphatic compounds in their properties. Example: Cyclopropane,Cyclohexane.
$(ii)$ Heterocyclic compounds: These are cyclic compounds in which the ring contains one or more atoms other than carbon (such as $N$,$O$,or $S$). These are called heteroatoms. Example: Furan,Pyridine,Thiophene.
$(iii)$ Non-benzenoid compounds: These are cyclic compounds that possess aromatic character but do not contain a benzene ring. They exhibit aromaticity due to the presence of a cyclic conjugated system following $H$ückel's rule $(4n+2) \pi$ electrons. Example: Azulene,Tropolone.