The statement(s) that correctly describe(s) the molecular orbital (MO) diagram of HO^. (hydroxyl radical) is/are (consider the O-H bond to be along the x-axis)

A. The Highest Occupied Molecular Orbital (HOMO) is a non-bonded MO that is predominantly formed with 2p_z and 2p_y atomic orbitals (AOs) of O-atom.

B. The HOMO is a sigma-bonded MO that is predominantly formed by the overlap of H (1s) and O (2s) AOs.

C. The sigma-bonding MO is formed by the overlap of H(1s) and O (2p_z) AOs.

D. The sigma-bonding MO is formed by the overlap of H (1s) and O (2p_x) AOs.

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Correct option is B

Statement-A: In the hydroxyl radical (HO^.), the oxygen atom has an unpaired electron in its 2p orbital. The 2pz and 2py atomic orbitals of the oxygen atom can combine with the 1s orbital of the hydrogen atom to form non-bonding molecular orbitals. The unpaired electron in the oxygen's 2p orbital contributes to the formation of these non-bonding MOs.
Thus, statement A is correct.

Statement-B: The HOMO in this case is actually a non-bonding MO formed by the oxygen 2pz and 2py orbitals, as mentioned in statement A. The 2s orbital of oxygen is not involved in the formation of the HOMO.
Thus, statement B is incorrect.

Statement-C: The sigma-bonding MO is primarily formed by the overlap of the hydrogen 1s orbital and the oxygen 2px orbital (statement D), not the 2pz orbital, thus statement C is incorrect.

Statement-D: The sigma-bonding molecular orbital is primarily formed by the overlap of the hydrogen 1s orbital and the oxygen 2px orbital. This leads to the formation of a sigma bond along the x-axis (O-H bond axis). Thus, statement D is correct.

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