Write the resonance structures for `N_2O_4` which has an `N-N` bond as suggested by experiments.

Explanation

Write the correct skeleton structure and explore all reasonable locations for a multiple bond.
Solution:
`N_2O_4` has `(2xx5)+(4xx6)=34` valence electrons. The most suitable skeleton structure is

The number of valence electrons remaining to complete octets is `34-10=24`. The number of valence electrons requuired to complete octets is 28. Thus, two additional bonds are required. Writing the possible combinations with the completed octets gives:

The correct structure of `N_2O_4`, the resonance hybrid, is an equal blend of these four contributing structures.