Lewis Structures — Prelims Questions

Which of the following molecules contains an atom that violates the octet rule by having an expanded octet?

What is the formal charge on the central nitrogen atom in the nitrate ion, $NO_3^-$?

How many lone pairs of electrons are present on the central atom in $XeF_4$?

Which of the following species exhibits resonance structures?

What is the total number of valence electrons in the $PO_4^{3-}$ ion?

In the most stable Lewis structure of $CO_2$, what is the bond order between carbon and each oxygen atom?