Draw the resonating structures of $(A)$ Ozone molecule $(O_3)$ and $(B)$ Nitrate ion $(NO_3^-)$.

(N/A) The resonating structures of the ozone molecule $(O_3)$ involve the delocalization of $\pi$ electrons. The two contributing structures are:
$O=O-O \leftrightarrow O-O=O$
$(B)$ The resonating structures of the nitrate ion $(NO_3^-)$ involve the delocalization of the double bond among the three oxygen atoms. The three contributing structures are:
$[O-N(=O)-O]^- \leftrightarrow [O=N(-O)-O]^- \leftrightarrow [O-N(-O)=O]^-$