[cor]

Four of the following are resonance forms of each other. Which one is not?


I think the correct answer is 5. Am I right?

[tmartin]

It's a little hard to see everything in your drawings, however I think I can see where all the negative charges are placed.  I wonder if there is an error in your drawing or if it is intentional (or maybe I just can't see the proper charge/symbol)?

What reasoning would you use to say #5 is not a resonance form?  Have you drawn out the electron flow on paper?  I find that can be helpful in avoiding confusion.

[cananian]

hi cor

i think the answer is no 4

you started resonance with lone pair  of oxygen with ( -1) charge, as we know  formal charge of the system should be the same before and after resonance.
hence where the radical come from?
could you please check formal charges for each


regards