NEET UG 2018 — Chemistry Inorganic Chemistry

Ion/Species	Total electron	Bond order
$\mathrm{NO}$NO	$15$15	$2.5$2.5
${\mathrm{CN}}^{-}$CN−	$14$14	$3$3
${\mathrm{CN}}^{+}$CN+	$12$12	$2$2
$\mathrm{CN}$CN	$13$13	$2.5$2.5

Number of ${e}^{-}$e− in $\mathrm{NO}=7+8=15$NO=7+8=15

$$\mathrm{NO}=\sigma 1{s}^{2}<\overset{*}{\sigma }1{s}^{2}<\sigma 2{s}^{2}<\overset{*}{\sigma }2{s}^{2}<\sigma 2{P}_{z}^{2}<\pi 2{P}_{y}^{2}=\pi 2{\mathrm{Px}}^{2}<\overset{*}{\pi }2{P}_{y}^{1}=\overset{*}{\pi }2{P}_{x}^{0}$$NO=σ1s2<σ∗1s2<σ2s2<σ∗2s2<σ2Pz2​<π2Py2​=π2Px2<π∗2Py1​=π∗2Px0​

Bond order $=\frac{\text{(number of electron in bonding molecular orbital − number of electron}\mathrm{in}\mathrm{anti}\mathrm{bonding}\mathrm{molecular}\mathrm{orbital})}{2}$=2(number of electron in bonding molecular orbital − number of electroninantibondingmolecularorbital)​

$\mathrm{BO}=\frac{6-1}{2}=2.5$BO=26−1​=2.5 .

Number of ${e}^{-}$e− in $\mathrm{CN}=6+7=13$CN=6+7=13

$\mathrm{NO}=\sigma 1{s}^{2}<\overset{*}{\sigma }1{s}^{2}<\sigma 2{s}^{2}<\overset{*}{\sigma }2{s}^{2}<\sigma 2{P}_{z}^{2}<\pi 2{P}_{y}^{2}=\pi 2{\mathrm{Px}}^{2}<\overset{*}{\pi }2{P}_{y}^{1}=\overset{*}{\pi }2{P}_{x}^{0}$NO=σ1s2<σ∗1s2<σ2s2<σ∗2s2<σ2Pz2​<π2Py2​=π2Px2<π∗2Py1​=π∗2Px0​.

Bond order $=\frac{5}{2} =2.5$=25​=2.5

Number of ${e}^{-}$e− in ${\mathrm{CN}}^{+}=6+7-1=12$CN+=6+7−1=12

$$\mathrm{NO}=\sigma 1{s}^{2}<\overset{*}{\sigma }1{s}^{2}<\sigma 2{s}^{2}<\overset{*}{\sigma }2{s}^{2}<\sigma 2{P}_{z}^{2}<\pi 2{P}_{y}^{2}=\pi 2{\mathrm{Px}}^{2}<\overset{*}{\pi }2{P}_{y}^{1}=\overset{*}{\pi }2{P}_{x}^{0}$$NO=σ1s2<σ∗1s2<σ2s2<σ∗2s2<σ2Pz2​<π2Py2​=π2Px2<π∗2Py1​=π∗2Px0​

Bond order $=\frac{ 4-0}{2} =2$=24−0​=2

${\mathrm{CN}}^{-}=$CN−= number of ${e}^{-}$e− in ${\mathrm{CN}}^{-}=6+7+1=14$CN−=6+7+1=14

$${\mathrm{CN}}^{-}=\sigma 1{s}^{2}<\overset{*}{\sigma }1{s}^{2}<\sigma 2{s}^{2}<\overset{*}{\sigma }2{s}^{2}<\sigma 2{P}_{z}^{2}<\pi 2{P}_{y}^{2}=\pi 2{\mathrm{Px}}^{2}<\overset{*}{\pi }2{P}_{y}^{1}=\overset{*}{\pi }2{P}_{x}^{0}$$CN−=σ1s2<σ∗1s2<σ2s2<σ∗2s2<σ2Pz2​<π2Py2​=π2Px2<π∗2Py1​=π∗2Px0​

$\mathrm{Bond}\mathrm{order}=\frac{6-0}{2}=3$Bondorder=26−0​=3 .

${\mathrm{CN}}^{-}$CN− as highest bond order.