Resonance structures can be written for

Which statement is true regarding the $PO_4^{3-}$ ion?
$A$. In $PO_4^{3-}$ ion,the $P-O$ bond order is $1.25$.
$B$. In $PO_4^{3-}$,the formal charge on each $O$ atom is $-0.75$.
$C$. $PO_4^{3-}$ shows four resonating structures.

Identify the relationship between the following two structures: $\begin{matrix} \overset{\Theta}{\overset{\centerdot \,\centerdot}{C}}H_2-C(=O)-CH_3 \end{matrix}$ and $\begin{matrix} CH_2=C(O^{\Theta})CH_3 \end{matrix}$

The resonance hybrid of the nitrate ion $(NO_3^-)$ is represented by:

Taking into account hybridization and resonance effects,rank the following $C-O$ bonds in order of decreasing bond length. The structure provided is the carbonate ion $(CO_3^{2-})$.

Explain the important aspects of resonance with reference to the $CO_{3}^{2-}$ ion.