Which of the following orders of resonance energy is correct?

Resonance in $X_2Y$ can be represented as shown in the image. The enthalpy of formation of $X_2Y$ $(X \equiv X(g) + \frac{1}{2} Y = Y(g) \rightarrow X_2Y(g))$ is $80 \ kJ \ mol^{-1}$. The magnitude of resonance energy of $X_2Y$ is $......... \ kJ \ mol^{-1}$ (nearest integer value). Given: Bond energies of $X \equiv X, X=X, Y=Y$ and $X=Y$ are $940, 410, 500$ and $602 \ kJ \ mol^{-1}$ respectively. Valence $X: 3, Y: 2$.

Draw the possible resonance structures for $CH_3 - \ddot{O} - CH_2^+$ and predict which of the structures is more stable. Give reason for your answer.

Explain the important aspects of resonance with reference to the $CO_3^{2-}$ ion.

Which of the two structures $A$ $(CH_3COOH)$ and $B$ $(CH_3COO^-)$ given below is more stabilised by resonance? Explain.

Compound in which all $C-N$ bond lengths are not same: