Q.

The total number of species from the following in which one unpaired electron is present, in ____________ .

N2,O2,C2-,O2-,O22-,H2+,CN-,He2+                              [2024]


Ans.

(4)

Molecule Electronic configuration Number of unpaired electrons
       N2 σ1s2<σ*1s2<σ2s2<σ*2s2<π2px2=π2py2<σ2pz2         0           
       O2 σ1s2<σ*1s2<σ2s2<σ*2s2<σ2pz2<π2px2=π2py2<π*2px1=π*2py1         2
       C2- σ1s2<σ*1s2<σ2s2<σ*2s2<π2px2=π2py2<σ2pz1         1
       O2- σ1s2<σ*1s2<σ2s2<σ*2s2<σ2pz2<π2px2=π2py2<π*2px2=π*2py1         1
       O22- σ1s2<σ*1s2<σ2s2<σ*2s2<σ2pz2<π2px2=π2py2<π*2px2=π*2py2         0
      H2+ σ1s1         1
     CN- σ1s2<σ*1s2<σ2s2<σ*2s2<π2px2=π2py2<σ2pz2         0
      He2+ σ1s2<σ*1s1         1