C10H6O2

from The Collaborative International Dictionary of English v.0.48

Naphthoquinone \Naph`tho*qui"none\, n. [Naphthalene + quinone.]
   (Chem.)
   A yellow crystalline substance, {C10H6O2}, analogous to
   quinone, obtained by oxidizing naphthalene with chromic acid.
   [1913 Webster]