Question

Number of species among the following which have a bond order of $1.5$ and are paramagnetic as well are

$H_2^{-};C_2^{+}$ and $F_2^{+}$

Answer 1

For checking the bond order and paramagnetism

we have to write the electronic configuration

1.$H_2^{-}$ (Total electrons$=3$)

Configuration...${\sigma }_{1s^2},{\sigma }_{1s^1}^{\ast }$

It is paramagnetic due to the presence of unpair electrons

Bond order$=\frac{2-1}{2}=0.5$

2.$C_2^{+}$ (Total electrons$=11$)

Configuration:- ${\sigma }_{1s^2},{\sigma }_{1s^2}^{\ast },{\sigma }_{2s^2},{\sigma }_{2s^2}^{\ast },{\pi }_{2p_x^2}{\pi }_{2p_y^2}$

Bond order$=\frac{7-4}{2}=1.5$

It is paramagnetic due to the presence of unpaired electrons

3.$F_2^{+}$ (Total electrons$=17$)

Configuration:-${\sigma }_{1s^2},{\sigma }_{1s^2}^{\ast },{\sigma }_{2s^2},{\sigma }_{2s^2}^{\ast },{\sigma }_{2p_z^2},\left({\pi }_{2p_x^2}{\pi }_{2p_y^2}\right),\left({\pi }_{2p_x^2}^{\ast }{\pi }_{2p_y^1}^{\ast }\right)$

Bond order$=\frac{10-7}{2}=1.5$

It is paramagnetic due to the presence of unpaired electrons

$\therefore$ Among the given species $2$ have a bond order$=1.5$ and are paramagnetic.