[Nb−Na] Nb= No of electrons in bonding molecular orbital Na= No of electrons in anti bonding molecular orbital (2) upto 14 electrons, molecular orbital configuration is
Here Na= Anti bonding electron =4 and Nb=10 (3) After 14 electrons to 20 electrons molecular orbital configuration is -
Here Na=10 and Nb=10 In O atom 8 electrons present, so in O2,8×2=16 electrons present. in O22− no of electrons =18 (A) Molecular orbital configuration of O22−(18 electrons) is σ1s2σ1s2*σ2s2σ2s2*σ2pz2π2px2=π2py2π2px2*=π2py2* ∴‌‌Nb=10 Na=8 ∴‌‌BO=‌
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[10−8]=1 (B) C22− has 14 electrons. Moleculer orbital configuration of C22− is σ1s2σ1s2*σ2s2σ2s2*π2px2=π2py2σ2pz2 ∴Na=4 Nb=10 ∴‌‌BO=‌
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[10−4]=3 (C) N22− has 16 electrons. Moleculer orbital configuration of N22− is σ1s2σ1s2*σ2s2σ2s2*π2px2=π2py2σ2pz2π2px1*=π2py1* ∴Na=6 Nb=10 ∴‌‌BO=‌
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[10−6]=2 The correct order of bond orders of C22−,N22− and O2‌2− O2‌2−<N2‌2−<C2‌2−