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?

$CH_2 = O \leftrightarrow \overset{\oplus}{C}H_2 - \overset{\ominus}{O} \leftrightarrow \overset{\ominus}{C}H_2 - \overset{\oplus}{O}$
Which of these structures is practically not a valid canonical structure for formaldehyde?

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.

Which is the most important contributing resonating structure of $[CH_2=N(=O)=O]^-$?

With respect to resonance structures of $CO_3^{2-}$ ion, which of the following statements are correct?
$(a)$ All $C – O$ bonds in $CO_3^{2-}$ are equivalent
$(b)$ There are three resonance structures possible for $CO_3^{2-}$ ion
$(c)$ The position of carbon and oxygen should change in every resonance structure
$(d)$ The formal charge on carbon atom is $0$

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