Dec 14, 2014 · The answer is C2- because of bond orders. When we draw the C2 MO, we have everything up till the PiPy Orbitlal filled, and the next orbital tht would be filled would be the sigma2Pz orbital. As for bond orders it is 1/2* [ (#e- in bonding orbitals)- (#e- in antibonding orbitals)] Doing this, normally just C2 is 1/2* [ (8)-4]=2.