(Solved): (a) Fill in any missing hydrogens and lone pair electrons in the structure of anion 3 (below), and ...

(a) Fill in any missing hydrogens and lone pair electrons in the structure of anion 3 (below), and use resonance structures to show how the negative charge is shared by two other carbons and by the nitro $\left({\mathrm{NO}}_2\right)$ group. (b) Fill in any missing hydrogens and lone pair electrons in the structure of cation 4 (above), and use resonance structures to show how the positive charge is shared by two other carbons and how the oxygen can also help stabilize the cation.