JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyApplication

JEE Main 25 July 2021, Shift 2, Chemistry Q31

Question 31 of 90 in this shift, Chemistry question 1 of 30, Section A.

In the following the correct bond order sequence is :

(1) $\mathrm{O_2 > O_2^{-} > O_2^{2-} > O_2^{+}}$
(2) $\mathrm{O_2^{+} > O_2^{-} > O_2^{2-} > O_2}$
(3) $\mathrm{O_2^{2-} > O_2^{+} > O_2^{-} > O_2}$
(4) $\mathrm{O_2^{+} > O_2 > O_2^{-} > O_2^{2-}}$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Chemical Bonding and Molecular Structure
Topic: Molecular Orbital Theory
Idea tested: Oxygen Ion Series Comparison

Same idea in other shifts

Asked 4× in all

2 Apr 2026, Shift 1 · Q53Given below are two statements : Statement (I) : The correct sequence of bond lengths in the following species is :…MediumTwo statements
26 Jun 2022, Shift 1 · Q64Consider the ions/molecule $\mathrm{O_2^+, O_2, O_2^-, O_2^{2-}}$ For increasing bond order the correct option is :EasySingle correct
26 Aug 2021, Shift 2 · Q32The bond order and magnetic behaviour of $\mathrm{O_2^-}$ ion are, respectively :MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.