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In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

In NMR, the nucleus independent chemical shift is used as a reference when working with molecules that exhibit this property. Also in NMR, molecules with this property exhibit a diamagnetic ring current. If half the vertices of a molecule's structure lie fully in the lower half of a Frost circle, it will have this property, which corresponds to no occupation of antibonding molecular orbitals. Molecules with this property generally show a high degree of unsaturation, but prefer substitution reactions to addition reactions. A molecule is said to have this property if it contains a fully-conjugated cyclic system. Four n plus two pi electrons is one criteria for this property put forth by Huckel. For 10 points, name this property of molecules like benzene, which exhibit unusual stability.
Output:
Science