Assuming 2 s – 2 p mixing is NOT operative, which of the following is not diamagentic?

Step-by-step solution

If the given molecule/atom/ion has all paired electrons in its orbitals, then it is said to be diamagnetic and if atleast one of the orbital has unpaired electron, then it is said to be paramagnetic. Writing the molecular orbital configuration of the given molecules assuming that no 2 s - 2 p mixing takes place- (i) B e 2 → σ 1 s 2 ,   σ * 1 s 2 ,   σ 2 s 2 ,   σ * 2 s 2 (diamagnetic) (ii) B 2 → σ 1 s 2 ,   σ * 1 s 2 ,   σ 2 s 2 ,   σ