What is the bond order of the carbon-carbon bond in benzene?

In graphite, the $C-C$ bond length $(141.5 \, pm)$ is found to be shorter than the normal $C-C$ single bond length $(154 \, pm)$. This anomaly occurs due to:

Which of the following resonance structures is more stable? Explain your answer.

Resonance is caused by the delocalization of which of the following?

What will be the resonance energy of $N_2O$ from the following data: $\Delta H_f(N_2O) = 82 \ kJ \ mol^{-1}$. Bond energies of $N \equiv N$,$N = N$,$O = O$,and $N = O$ bonds are $946$,$418$,$498$,and $607 \ kJ \ mol^{-1}$ respectively.

Compare the relative stability of the following resonating structures:
$(i)$ $CH_3-CH=C(CN)-COCH_3$
(ii) $CH_3-CH=C(CN)-C^+(O^-)CH_3$
(iii) $CH_3-C^+(H)-C(CN)=C(O^-)CH_3$
(Note: The structures are provided in the image.)