Answer
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Work Step by Step
Figs. 4-47 and 4-49 show different predictions for the molecular orbitals of B2. The reason is that these figures use different sequences for filling the molecular orbitals. Because B2 is paramagnetic, the p2p and s2p molecular orbitals must be switched from the first prediction. The s2p is lower in energy than p2p because the 2s AO has better overlap with the 2p AOs, leading to greater stabilization of the s2p molecular orbital. Diatomic oxygen cannot help decide between s2p and p2p because O2 has a different electron configuration (σ2s^2σ2s^2π2p^4π2p^2).
