Explain that aromaticity decrease in the order : Benzene > Napthalene > Anthracene

Naphthalene has two aromatic rings, but only 10 pi electrons (rather than the twelve electrons that it would prefer). This means that naphthalene has less aromatic stability than two isolated benzene rings would have. ... Benzene has six pi electrons for its single aromatic ring.

Similarly anthracene is has three benzene ring but four electrons are shared between two benzene ring it should have 18 pi electron but actually 14 pi electron is consist with this anthracene so aromaticity decreases !

Benzene > Naphthalene > Anthracene