Resonance is due to

Caliene,$C_7H_6$,is expected to be a fairly polar aromatic molecule. Which of the following resonance forms contributes to the greatest extent towards the real structure (resonance hybrid) of the molecule?

Resonance in carbonate ion $CO_3^{2-}$ is shown below. Which of the following statements is true?

During the formation of the dimer $N_2O_4$ from two molecules of $NO_2$,the odd electron on the nitrogen atom of each $NO_2$ molecule pairs up. What is the resulting structure?

Select the correct statement about $HCO_3^-$:

Explain why the following two structures,$I$ and $II$,cannot be the major contributors to the real structure of $CH_{3}COOCH_{3}$.
$I: CH_{3}-C^{+}(O^{-})-OCH_{3}$
$II: CH_{3}-C(=O^{-})-OCH_{3}^{+}$