2022 Chemical Bonding and Molecular StructureMolecular Orbital Theory Medium Question 4 of 20 in Molecular Orbital Theory

Which amongst the following is incorrect statement

A $O_2^+$ ion is diamagnetic.
B The bond orders of $O_2^+$, $O_2$, $O_2^-$ and $O_2^{2-}$ are 2.5, 2, 1.5 and 1, respectively
C $C_2$ molecule has four electrons in its two degenerate $\pi$ molecular orbitals.
D $H_2^+$ ion has one electron.

The answer is A.

Solution

$O_2^+$ has 15 electrons, so it contains one unpaired electron. Hence it is paramagnetic, not diamagnetic – so this statement is incorrect. (Bond orders of $O_2^+$, $O_2$, $O_2^-$, $O_2^{2-}$ are 2.5, 2, 1.5, 1; $C_2$ has 4 electrons in two degenerate $\pi$ MOs; $H_2^+$ has one electron – all correct.)

Concept magnetism and bond order of diatomic species

Molecular Orbital Theory in past papers

20 questions from this chapter have appeared across 13 exam years.