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Question: Answered & Verified by Expert
In which of the following ionization processes the bond energy increases and the magnetic behaviour changes from paramagnetic to diamagnetic:
ChemistryChemical Bonding and Molecular StructureNEETNEET 2013 (Karnataka)
Options:
  • A $\mathrm{O}^2 \rightarrow \mathrm{O}_2^{+}$
  • B $\mathrm{C}_2 \rightarrow \mathrm{C}_2^{+}$
  • C $\mathrm{NO} \rightarrow \mathrm{NO}^{+}$
  • D $\mathrm{N}_2 \rightarrow \mathrm{N}_2^{+}$
Solution:
2043 Upvotes Verified Answer
The correct answer is: $\mathrm{NO} \rightarrow \mathrm{NO}^{+}$
The molecular configuration is depicted below:
Molecular orbital configuration of
$$
\begin{aligned}
& \mathrm{O}_2 \Rightarrow \sigma 1 s^2 \rightarrow \sigma^* 1 \mathrm{~s}^2 \rightarrow \sigma 2 s^2 \rightarrow \sigma^* \\
& 2 s^2 \rightarrow \sigma 2 \mathrm{p}_z^2 \pi 2 p^2{ }_x \rightarrow \pi 2 p^2{ }_y \\
& \pi^* 2 \mathrm{p}_x^1 \rightarrow \pi^* 2 p^1{ }_y \\
& \Rightarrow \text { Paramagnetic } \\
& \text { Bond order }=\frac{10-6}{2}=2 \\
& \mathrm{O}_2^{+} \Rightarrow \sigma 1 s^2 \rightarrow \sigma^* 1 s^2 \rightarrow \sigma 2 s^2 \rightarrow \\
& \sigma^* 2 s^2 \rightarrow \sigma 2 p^2{ }_z \rightarrow \pi 2 \mathrm{p}_x^2 \\
& \pi 2 p^2{ }_y \rightarrow \pi^* 2 p^1{ }_x \\
& \Rightarrow \text { Paramagnetic } \\
& \text { Bond order }=\frac{10-5}{2}=2.5 \\
& \mathrm{C}_2 \Rightarrow \sigma 1 s^2 \rightarrow \sigma^* 1 s^2 \rightarrow \sigma 2 s^2 \rightarrow \\
& \sigma^* 2 s^2 \rightarrow \pi 2 p^2{ }_x \rightarrow \pi 2 p^2 \\
& \Rightarrow \text { Diamagnetic } \\
& \text { Bond order }=\frac{8-4}{2}=2 \\
& \mathrm{C}_2^{+} \Rightarrow \sigma 1 s^2 \rightarrow \sigma^* 1 s^2 \rightarrow \sigma 2 s^2 \rightarrow \\
& \sigma^* 2 s^2 \rightarrow \pi 2 p^2{ }_x \rightarrow \pi 2 p^1{ }_y
\end{aligned}
$$



$$
\begin{aligned}
& \Rightarrow \text { Paramagnetic } \\
& \text { Bond order }=\frac{7-4}{2}=15 \\
& \mathrm{NO} \Rightarrow \sigma 1 s^2 \rightarrow \sigma^* 1 s^2 \rightarrow \sigma 2 s^2 \rightarrow \\
& \sigma^* 2 s^2 \rightarrow \sigma 2 p^2=\pi 2 p_x^2 \rightarrow \\
& \pi 2 p_y^2 \rightarrow \pi^* 2 p_x^1 \\
& \Rightarrow \text { Paramagnetic } \\
& \text { Bond order }=\frac{10-5}{2}=2.5 \\
& \mathrm{NO}^{+} \Rightarrow \sigma 1 s^2 \rightarrow \sigma^* 1 s^2 \sigma 2 s^2 \rightarrow \sigma^* 2 s^2 \\
& \sigma 2 p_z^2 \rightarrow \pi 2 p_x^2 \rightarrow \pi 2 p_y^2 \\
& \Rightarrow \text { Diamagnetic } \\
& \text { Bond } \text { order }=\frac{10-4}{2}=3 \\
& \mathrm{~N}_2 \Rightarrow \sigma 1 s^2 \rightarrow \sigma^* 1 s^2 \sigma 2 s^2 \rightarrow \sigma^* 2 s^2 \\
& \rightarrow \pi 2 p_x^2 \rightarrow \pi 2 p_y^2 \rightarrow \sigma 2 p^1= \\
& \Rightarrow \text { Paramagnetic } \\
& \text { Bond order }=\frac{10-4}{2}=3 \\
& \mathrm{~N}_2^{+} \Rightarrow \sigma 1 s^2 \sigma^* 1 s^2 \sigma 2 s^2 \sigma^* 2 s^2 \pi 2 p^2{ }_x \\
& \pi 2 p^2 \sigma 2 p_z^1 \\
& \Rightarrow \text { Paramagnetic } \\
& \text { Bond order }=\frac{9-4}{2}=2.5 \\
&
\end{aligned}
$$

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