According to MOT (a) O2+(15e−)=σ1s2σ1s*2σ2s2σ2s*2σ2p22(π2px2=π2py2)(π2pz*1=π2py*0) Number of unpaired e−s=1⇒ Paramagnetic (b) O2−(17e−)=σ1s2σ1s*2σ2s2σ2s*2σ2p22(π2px2=π2py2)(π2px*2=π2py*1) Number of unpaired e−s=1 (c) O2(16e−)=σ1s2σ1s*2σ2s2σ2s*2σ2p22(π2px2=π2py2)(π2px*1=π2py*1) Number of unpaired e−s=2⇒ paramagnetic (d) O22−(18e−)=σ1s2σ1s*2σ2s2σ2s*2σ2p22(π2px2=π2py2)(π2px*2=π2py*2) Number of unpaired e−s=0=> diamagnetic