For which of the following can resonance structures be drawn? Why?
$CO_2, NO_2, O_3, O_2, CH_4$

(N/A) Resonance structures can be drawn for $CO_2, NO_2,$ and $O_3$.
Resonance occurs in molecules where there is a system of conjugated double bonds or where a central atom has a lone pair of electrons and is bonded to atoms with different electronegativities or multiple bonds,allowing for the delocalization of $\pi$ electrons.
In $CO_2, NO_2,$ and $O_3$,the presence of multiple bonds and lone pairs allows for the shifting of electrons to create different resonance contributors.
$O_2$ and $CH_4$ do not exhibit resonance because $O_2$ is a homonuclear diatomic molecule with a simple double bond,and $CH_4$ has only single bonds with no lone pairs on the central carbon atom.