Question

The molecule/ion having diamagnetic nature and a bond order of $1.0$ is

• A. $He^{+}_2$
• B. $Li^{+}_2$
• C. $B_2$
• D. None

Answer 1

Answer: (A)

$He _{2}^{+}= \sigma \,1 s^{2}<\, \sigma^{*} \,1 s^{1}$

$BO =\frac{2-1}{2}=0.5$

$He _{2}^{+}$ ion having one unpaired electron. So, it is paramagnetic.

$ Li _{2}^{+}=\sigma \,1 s^{2}<\, \sigma^{*} 1 s^{2}<\,\sigma 2 s^{1} $

$ BO =\frac{3-2}{2}=0.5$ (Paramagnetic)

$B _{2}=\sigma \,1 s^{2}<\,\sigma^{*} 1 s^{2}<\,\sigma 2 s^{2}<\,\sigma^{*} 2 s^{2}<\,\pi 2 p_{x}^{1}=\pi 2 p_{y}^{l}$

$BO =\frac{6-4}{2} =1$ (Paramagnetic)

$ C _{2} \rightarrow \sigma \,1s ^{2}<^{*} \sigma 1s^{2}<\, \sigma 2 s^{2}<* \sigma 2 s^{2}<\,\pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}$

$BO =\frac{8-4}{2}=2$ (Diamagnetic)