Question

Which one of the following species is diamagnetic in nature?
(a) $He_{2}^{+}$
(b) ${{H}_{2}}$
(c) $H_{2}^{+}$
(d) $H_{2}^{-}$

Answer 1

Hint: Diamagnetic species are those species that consist of the paired electrons and to find it, first of all, you should know how many electrons are present in each of the above-given species and then, from that, you can easily recognize the species having paired electrons in their valence shell. Now solve it.

Complete step by step answer:
First of all, let’s discuss what are diamagnetic species. Diamagnetic species are those species that do not have any paired electrons in their valence shell and such substances or the species are weakly repelled by the magnet when placed in the magnetic field.
Now consider the statement as:
First, we will calculate the number of electrons present in each of the given species and then, we can easily identify which of them is a diamagnetic species.

Species	No. of electrons present	Paired/unpaired	Paramagnetic/diamagnetic
$He_{2}^{+}$	Three	unpaired	Paramagnetic
${{H}_{2}}$	Two	Paired	diamagnetic
$H_{2}^{+}$	One	Unpaired	Paramagnetic
$H_{2}^{-}$	Three	Unpaired	Paramagnetic

So, thus, from the above table, we come to know that ${{H}_{2}}$ is a diamagnetic species.
So, the correct answer is “Option B”.

Note: Don’t get confused in the paramagnetic and diamagnetic substances.
By the diamagnetic species or substances we simply, mean the absence of the unpaired electrons, and such species are weakly repelled by the magnetic.
- While on the other hand by the paramagnetic substances, we mean the presence of the unpaired electron, and substances are strongly attracted towards the magnetic when they are placed in three magnetic fields.