8.1. Organic chemistry Nomenclature of organic compounds — Chemistry STD 11 Science — Question

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A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its rings. Phenol has one hydroxy group outside the carbon ring and aniline has one nitrogen atom outside the carbon ring. So they are not heterocyclic compound. Furan has one oxygen atom inside ring and pyridine has one nitrogen atom inside ring.