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

Which of the following compounds does not exhibit the resonance effect?

Given below are two statements :
Statement $I$ : Experimentally determined oxygen-oxygen bond lengths in the $O_3$ are found to be same and the bond length is greater than that of a $O=O$ (double bond) but less than that of a single $(O-O)$ bond.
Statement $II$ : The strong lone pair-lone pair repulsion between oxygen atoms is solely responsible for the fact that the bond length in ozone is smaller than that of a double bond $(O=O)$ but more than that of a single bond $(O-O)$.
In the light of the above statements,choose the correct answer from the options given below:

Delocalised molecular orbitals are found in

The number of resonance structures for $N$ is

In $BF_3$ molecule: