Chemistry - CHEMICAL BONDING Question with Solution | TestHub

For the B₂ molecule, the total number of electrons is 10 ($5+5$), with 2 electrons occupying the 2p molecular orbitals. In the energy level sequence for B₂, the ${\pi }_{2p}$ orbitals are lower in energy than the ${\sigma }_{2p}$ orbital. Following Hund's Rule, these two electrons must occupy the degenerate ${\pi }_{2p}$ orbitals singly with parallel spins.

(A) and (D) are incorrect because they pair electrons in a single orbital, violating Hund's rule.

(B) is incorrect because the spins are opposite rather than parallel.

(C) is incorrect because it violates the Aufbau principle by placing an electron in the higher-energy $\sigma$ orbital before filling the $\pi$ orbitals.

Therefore, all options represent incorrect ground state configurations.