Biphenyl has the following structure. (a) Is biphenyl a (fused) polynuclear aromati...

Biphenyl has the following structure.

(a) Is biphenyl a (fused) polynuclear aromatic hydrocarbon?

(b) How many pi electrons are there in the two aromatic rings of biphenyl? How does this number compare with that for naphthalene?

(c) The heat of hydrogenation for biphenyl is about 418 kJ/mol (100 kcal/mol). Calculate the resonance energy of biphenyl.

(d) Compare the resonance energy of biphenyl with that of naphthalene and with that of two benzene rings. Explain the difference in the resonance energies of naphthalene and biphenyl.