BITSAT 2013 Paper

B2 and O2 are paramagnetic due to presence of unpaired electron. MO electronic configuration of B2 is :
σ 1s2 σ* 1s2 σ 2s2 σ* 2s2 π2px1 = π2py1
MO electron i.e. configuration of O2 is :
σ 1s2 σ* 1s2 σ 2s2 σ* 2s2 π2pz1π2px1
= π2py2π*2px1 = π*2py1