Electronic configuration of C2 i.e. X1 is σ1s2σls*2σ2s2σ2s*2π2px2π2py2 So, bond order Number of bonding orbital electrons - =
Number of antibonding orbital electrons
2
=
8−4
2
=
4
2
=2 Electronic configuration of i.e. N2 i.c. X2 is σ1s2σ1s*2σ2s2σ2s+2σ2pz2π2px2π2py2 Bond order =
10−4
2
=
6
2
=3 Electronic configuration of B2 i.e. X3 is σ1s2σls*2σ2s2σ2s*2π2px1.2π2py1 Bond order =
6−4
2
=
2
2
=1 So, order of bond order (BO) is BO2>BO1>BO3 Now, since bond order and bond lengths are inversely proportional. Hence, order of bond length isX3>X1>X2