Discussion Forum

1)

How many of the following species are diamagnetic?

$He_{2}^{+}, H_{2}^{+}, H_{2}^{-}, He$

Answer:

Option B

Explanation:

 According to molecular orbital theory  , species with all paired electrons  in their electronic configuration are diamagnetic in nature

$He^{+}_{2}\rightarrow $  Has total 3 electrons , thus it contains one unpaired electron and is paramagnetic in nature.

$H_{2}\rightarrow $ Has total 2 electrons , thus it contains all paired electrons and is diamagnetic in nature

$H^{-}_{2}\rightarrow $ Has only 1 electron, thus it is paramagnetic in nature

$H^{2}_{2}\rightarrow $ Has total 3 electrons, thus it contains  one unpaired electron and is paramagnetic in nature

$He \rightarrow $  Contains total two (2) electrons and has no unpaired electron, thus is diamagnetic in nature.

 Hence , among the given species, we have only two of them which are diamagnetic and thus, option (b) is the correct answer.