Final answer:
Furan is an aromatic compound due to its planar five-membered ring structure that allows for electron delocalization, conforming to Hückel's rule.
Step-by-step explanation:
Furan is a heteroaromatic compound which means that it is classified as aromatic rather than antiaromatic or nonaromatic. Aromatic compounds typically possess a cyclic, planar structure with conjugated π-systems that allow for electron delocalization.
Furan fulfils the criteria for aromaticity because it has a planar ring of four carbon atoms and one oxygen atom, making it a five-membered ring where the oxygen atom's lone pair of electrons contributes to the π-system, thus following Hückel's rule of 4n+2 π-electrons (n=1 for furan).
In contrast, pyrrole is another heterocyclic compound with aromatic character, but furan and pyrrole are distinct compounds. The number sequences such as '75 46' or '73 90' do not relate directly to furan's aromatic classification.