Which one of the following is not a resonance structure for no21−? o with a pair of electrons above and below, a double-bond to the n with a pair of electrons above, a single-bond to the o with three pairs of electrons around it. the whole thing is labeled with a -1. o with a pair of electrons above and below, a double-bond to the n with a pair of electrons above, a double-bond to the o with two pairs of electrons around it. the whole thing is labeled with a -1. o with three pairs of electrons around it, a single-bond to the n with a pair of electrons above, a double-bond to the o with two pairs of electrons. the whole thing is labeled with a -1. all of the above are resonance structures for no21−.