[tashkent]

Greetings!

I am having problems with molecular orbitals and isoelectronic species.  I would like to cite this #19 problem of the GRE Chemistry practice book:

19) The azide ion, N3-, is isoelectronic with which of the following?

a) NO2-
b) NO2
c) CO2
d) SO2
e) O3

Are there any references or books so I can refer to the molecular orbital diagrams of these species?  I have tried Douglas & Mcdaniel, Huheey and Miessler & Tarr but I did not succeed.  The answer is letter C.  

Hope to hear from you guys.  Thanks!

Sincerely,
Tashkent

[Demotivator]

Don't need molecular orbitals. Isoelectronic means equal number of electrons. Just count the  electrons.