JEE Main 2021 · ChemistryMultiple choiceSingle correctMediumApplication

JEE Main 25 February 2021, Shift 1, Chemistry Q32

Question 32 of 90 in this shift, Chemistry question 2 of 30, Section A.

According to molecular orbital theory, the species among the following that does not exist is :

(1) $\mathrm{O_2^{2-}}$
(2) $\mathrm{He_2^{-}}$
(3) $\mathrm{Be_2}$ Official answer
(4) $\mathrm{He_2^{+}}$

Official answer

Option 3

NTA final key.

Chapter: Chemical Bonding and Molecular Structure
Topic: Molecular Orbital Theory
Idea tested: Bond Order Calculation

Same idea in other shifts

Asked 11× in all

8 Apr 2024, Shift 2 · Q83Number of molecules having bond order 2 from the following molecules is ________. $\mathrm{C_2}$ , $\mathrm{O_2}$ , $\mathrm{Be_2}$ ,…MediumNumerical value
29 Jan 2024, Shift 1 · Q82The number of species from the following which are paramagnetic and with bond order equal to one is ________.…MediumNumerical value
27 Jul 2022, Shift 1 · Q85According to MO theory, number of species/ions from the following having identical bond order is__.…MediumNumerical value
27 Jul 2022, Shift 2 · Q62Match **List - I** with **List - II**. List - I (A) $\psi_{MO}=\psi_A-\psi_B$ (B) $\mu=Q\times r$ (C) $\frac{N_b-N_a}{2}$ (D)…EasyMatch the list
30 Jul 2022, Shift 2 · Q52On the basis of MO. theory, the number of molecules from the following which have bond order two, is ________. $\mathrm{O_2}$ ,…MediumNumerical value
24 Jun 2022, Shift 2 · Q63The correct order of bond orders of C $_2^{2-}$ , N $_2^{2-}$ and O $_2^{2-}$ is, respectivelyMediumSingle correct
25 Jun 2022, Shift 1 · Q61Bonding in which of the following diatomic molecule(s) become(s) stronger, on the basis of MO Theory, by removal of an electron ? (A)…MediumOther
4 Aug 2021, Shift 2 · Q54The bond order in $\mathrm{NO^+}$ is ________ . ( integer answer)EasyNumerical value

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.