Chemistry - GOC Question with Solution | TestHub

The benzoyl unit (ring + $\mathrm{C}=\mathrm{O}$, 8 atoms) is one system. The $\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_2$ unit is $\mathrm{s}{\mathrm{p}}^3$ and breaks conjugation, so the second phenyl ring (6 atoms) is a separate system. Total = 2.