JEE Main 2019 — Chemistry Inorganic Chemistry

2019mcqmedium

Among the following molecules/ ions,

${C}_{2}^{2-}, {N}_{2}^{2-},{O}_{2}^{2-}, {O}_{2}$

Which one is diamagnetic and has the shortest bond length?

Official previous-year question

Held on 8 Apr 2019 · Verified 6 Jul 2026.

Options

A
${N}_{2}^{2-}$
B
${O}_{2}^{2-}$
C
${O}_{2}$
D
${C}_{2}^{2-}$

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Solution

${{O}_{2}}_{(16)}= \sigma 1{s}^{2}{\sigma }^{*}1{s}^{2} \sigma 2{s}^{2} {\sigma }^{*}2{s}^{2} \sigma 2{p}_{z}^{2} \pi 2{p}_{x}^{2}=\pi 2{p}_{y}^{2}$ ${\pi }^{*} 2{p}_{x}^{1}=\pi 2{p}_{y}^{1}$

Paramagnetic; Bond order $= 2$

${{O}_{2}^{2-}}_{(18)}= \sigma 1{s}^{2}{\sigma }^{*}1{s}^{2} \sigma 2{s}^{2} {\sigma }^{*}2{s}^{2} \sigma 2{p}_{z}^{2} \pi 2{p}_{x}^{2}=\pi 2{p}_{y}^{2}$ ${\pi }^{*} 2{p}_{x}^{2}={\pi }^{*}2{p}_{y}^{2}$

Diamagnetic; Bond order $= 1$

${{N}_{2}^{2-}}_{(16)}= \sigma 1{s}^{2}{\sigma }^{*}1{s}^{2} \sigma 2{s}^{2} {\sigma }^{*}2{s}^{2} \pi 2{p}_{x}^{2} \pi 2{p}_{y}^{2} \sigma 2{p}_{z}^{2}{\pi }^{*}2{p}_{x}^{1} ={\pi }^{*}2{p}_{y}^{1}$

Paramagnetic; Bond order $= 2$

${{C}_{2}^{2-}}_{(14)}= \sigma 1{s}^{2}{\sigma }^{*}1{s}^{2} \sigma 2{s}^{2} {\sigma }^{*}2{s}^{2} \pi 2{p}_{x}^{2}=\pi 2{p}_{y}^{2} \sigma 2{p}_{z}^{2}$

Diamagnetic; Bond order $=3$

Bond order $\propto \frac{1}{Bond length}$

Hence ${C}_{2}^{2}$ is diamagnetic and is having shortest bond length.

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Solution

${{O}_{2}}_{(16)}= \sigma 1{s}^{2}{\sigma }^{*}1{s}^{2} \sigma 2{s}^{2} {\sigma }^{*}2{s}^{2} \sigma 2{p}_{z}^{2} \pi 2{p}_{x}^{2}=\pi 2{p}_{y}^{2}$ ${\pi }^{*} 2{p}_{x}^{1}=\pi 2{p}_{y}^{1}$

Paramagnetic; Bond order $= 2$

Diamagnetic; Bond order $= 1$

${{N}_{2}^{2-}}_{(16)}= \sigma 1{s}^{2}{\sigma }^{*}1{s}^{2} \sigma 2{s}^{2} {\sigma }^{*}2{s}^{2} \pi 2{p}_{x}^{2} \pi 2{p}_{y}^{2} \sigma 2{p}_{z}^{2}{\pi }^{*}2{p}_{x}^{1} ={\pi }^{*}2{p}_{y}^{1}$

Paramagnetic; Bond order $= 2$

${{C}_{2}^{2-}}_{(14)}= \sigma 1{s}^{2}{\sigma }^{*}1{s}^{2} \sigma 2{s}^{2} {\sigma }^{*}2{s}^{2} \pi 2{p}_{x}^{2}=\pi 2{p}_{y}^{2} \sigma 2{p}_{z}^{2}$

Diamagnetic; Bond order $=3$

Bond order $\propto \frac{1}{Bond length}$

Hence ${C}_{2}^{2}$ is diamagnetic and is having shortest bond length.

JEE Main 2019 — Chemistry Inorganic Chemistry

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JEE Main 2019 — Chemistry Inorganic Chemistry

Options

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Solution

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JEE Main Inorganic Chemistry in other years

More JEE Main Inorganic Chemistry questions

Other Chemistry topics for JEE Main

Physical Chemistry

Organic Chemistry

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