How many of the following species are diamagnetic ?
`He_2^(+) , H_2 , H_2^(+) , H_2^(-) , He`

Options

A. 1
B. 2
C. 3
D. 0

Answer

B

Explanation

According to molecular orbital theory, species with all paired electrons in their electronic configuraction are diamagnetic in nature. `He_(2)^(+) rarr` Has total 3 electrons, thus it contain one unpaired electron and is paramagnetic in nature. `H_(2) rarr` Has total 2 electrons, thus it contains all paired electrons and is diamagnetic in nature. `H_(2)^(+) rarr` Has only 1 electron, thus it is paramagnetic in nature.
`H_(2)^(-) rarr` Has total 3 electrons, thus it contains one unpaired electron and is paramagnetic in nature. `He rarr` 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.