JEE Main · Chemistry · Chemical Bonding and Molecular Structure
Molecular Orbital Theory: JEE Main previous year questions
34 questions in the 108 JEE Main shifts Lumi analysed, in 7 of 8 years. Pattern: Asked most years. 12 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 34
- in 33 of 108 shifts
- Years asked
- 7/8
- last asked 2026
- Weighted estimate
- 0.2
- model; history: 0.3 a shift on average, typically 0.1–0.5
Key findings
- 01
Asked in 7 of 8 years with analysed shifts and in 33 of 108 shifts: 34 questions, #103 of 196 topics. The years that asked it were 1.5 apart on average.
- 02
48% of its questions since 2020 tested an idea no earlier year had asked; 14 repeated an idea from the year before.
- 03
The most repeated idea is Bond Order Calculation, asked 11 times in 11 shifts (2021, 2022, 2024), most often as “count species by magnetism and bond order”.
- 04
JEE Main has asked 11 of the 54 ideas in this topic; 34 have never been asked, directly or inside another question.
- 05
Mostly asked as numerical value (44%); 44% need a numerical answer, 32% are easy and 0% hard.
- 06
The skill tested most is conceptual (26%), then application (26%).
Questions a shift, year by year
Out of the 25 Chemistry questions in a shift. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift.
Raw count: 2017: 1 in 1 shift · 2020: 2 in 12 shifts · 2021: 8 in 24 shifts · 2022: 9 in 24 shifts · 2023: 2 in 12 shifts · 2024: 10 in 18 shifts · 2025: 0 in 8 shifts · 2026: 2 in 9 shifts.
- Up to 2023
- 0.3
- a shift, of 25
- Since 2024
- 0.2
- -0.1
- Usual gap
- 1.5 yrs
- between years asking it
- Shifts with it
- 33/108
- 31% of analysed shifts
How it is asked
Difficulty, format and skill
Across all 34 questions on Molecular Orbital Theory since 2017.
Difficulty
QUESTIONS- Easy11 · 32%
- Medium23 · 68%
- Hard0 · 0%
Format
SHARE- Numerical value · 15 Q44%
- Single correct · 12 Q35%
- Two statements · 2 Q6%
- Other · 2 Q6%
- Match the list · 2 Q6%
- Diagram based · 1 Q3%
Skill tested
SHARE- Conceptual · 9 Q26%
- Application · 9 Q26%
- Calculation · 6 Q18%
- Multi-step · 5 Q15%
- Recall · 4 Q12%
- Diagram reading · 1 Q3%
Repeats
New idea, or one asked before?
Each column is a year. Blue questions tested an idea no earlier year had asked; navy ones went back to an idea from an earlier year. 2017 is the first year, so everything in it counts as new. Heights are question counts, and Lumi analysed 1 to 24 shifts a year, so compare the split inside a column rather than heights across years.
- Idea asked for the first time
- Idea asked in an earlier year
Coverage of the topic
JEE Main has asked 11 of the 54 ideas in this topic. 34 have never been asked yet.
- Asked directly11 · 20%
- Touched inside another question9 · 17%
- Never asked34 · 63%
Ideas come from Lumi’s JEE syllabus map. A never-asked idea is not a safe skip: across all of JEE Main, 22% of questions since 2024 tested an idea no earlier year had asked.
Drill down
Chapter, idea, question
Every idea JEE Main tested in this topic, with its eight years. Open one to read the questions.
10 ideas inside
Squares are the 8 years with analysed shifts, 2017 to 2026. A number is the questions that year when there is more than one; the shade is scaled to one shift, so a year with more analysed shifts (1 to 24 a year) does not look darker. Share is of the level above.
Ideas
Every idea inside this topic
11 different ideas were tested; 4 came more than once.
count species by magnetism and bond order
Numerical value · 11 shifts · 6 numericalcount species with unpaired electrons
Numerical value · 9 shifts · 5 numericalstatement i/ii on bond length and unpaired electrons
Single correct · 4 shiftstrue statement selection on lcao conditions
Numerical value · 3 shifts · 1 numericalidentify molecular orbital diagram
Diagram based · 1 shiftelectrons in antibonding orbitals
Numerical value · 1 shift · 1 numericalsum of bond orders of diatomics
Numerical value · 1 shift · 1 numericalstatements on pi bonding and antibonding mo nodes
Two statements · 1 shiftspecies matching acetylide bond order and magnetism
Single correct · 1 shiftcount complexes with synergic bonding
Numerical value · 1 shift · 1 numericalorder of bond strength in no species
Single correct · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Bond Order Calculationcount species by magnetism and bond order | 11 | 11 | Numerical valueApplication | 6 | |
| Magnetic Property Predictioncount species with unpaired electrons | 9 | 9 | Numerical valueApplication | 5 | |
| Oxygen Ion Series Comparisonstatement i/ii on bond length and unpaired electrons | 4 | 4 | Single correctConceptual | – | |
| LCAO and MO Formationtrue statement selection on lcao conditions | 3 | 3 | Numerical valueRecall | 1 | |
| Nodal Planes in Molecular Orbitalsidentify molecular orbital diagram | 1 | 1 | Diagram basedDiagram reading | – | |
| Counting Antibonding Electronselectrons in antibonding orbitals | 1 | 1 | Numerical valueCalculation | 1 | |
| Isoelectronic Bond Order Shortcutsum of bond orders of diatomics | 1 | 1 | Numerical valueCalculation | 1 | |
| Symmetry of Pi Molecular Orbitalsstatements on pi bonding and antibonding mo nodes | 1 | 1 | Two statementsConceptual | – | |
| Isoelectronic Species Principle in MOTspecies matching acetylide bond order and magnetism | 1 | 1 | Single correctConceptual | – | |
| LUMO as Pi-Acceptorcount complexes with synergic bonding | 1 | 1 | Numerical valueConceptual | 1 | |
| Bond Stability Comparisonorder of bond strength in no species | 1 | 1 | Single correctApplication | – |
Times and shifts count every analysed shift. Across JEE Main, 78% of questions since 2024 went back to an idea an earlier year had asked; the rest were new. All repeated ideas
Every question
Molecular Orbital Theory questions, year by year
The opening words of each question as it appeared in the official paper, with the idea it tested. Open one for its options and the official answer.
JEE Main 20262 questions in 2 shifts
- 2 Apr, Shift 1Q53Given below are two statements : Statement (I) : The correct sequence of bond lengths in the following species is :…
Idea: Oxygen Ion Series Comparison
MediumTwo statements - 4 Apr, Shift 2Q53Which of the following pictorial diagram most correctly represents the (-antibonding) molecular orbital between two atoms if…
Idea: Nodal Planes in Molecular Orbitals
New ideaMediumDiagram based · figure
JEE Main 202410 questions in 9 shifts
- 4 Apr, Shift 1Q82Number of molecules/species from the following having one unpaired electron is ________. , , NO,…
Idea: Magnetic Property Prediction
Asked the year beforeMediumNumerical value - 8 Apr, Shift 2Q61When and are the wave functions of atomic orbitals, then is represented by :
Idea: LCAO and MO Formation
New ideaEasySingle correct - 8 Apr, Shift 2Q83Number of molecules having bond order 2 from the following molecules is ________. , , ,…
Idea: Bond Order Calculation
MediumNumerical value - 9 Apr, Shift 1Q82The total number of species from the following in which one unpaired electron is present, is ________.…
Idea: Magnetic Property Prediction
Asked the year beforeMediumNumerical value - 9 Apr, Shift 2Q82Total number of electrons present in molecular orbitals of , and is ________.
Idea: Counting Antibonding Electrons
New ideaEasyNumerical value - 1 Feb, Shift 2Q62Given below are two statements : Statement (I) : A bonding MO has lower electron density above and below the inter-nuclear axis.…
Idea: Symmetry of Pi Molecular Orbitals
New ideaMediumTwo statements - 27 Jan, Shift 1Q83Sum of bond order of CO and is __________.
Idea: Isoelectronic Bond Order Shortcut
New ideaEasyNumerical value - 29 Jan, Shift 1Q82The number of species from the following which are paramagnetic and with bond order equal to one is ________.…
Idea: Bond Order Calculation
MediumNumerical value - 30 Jan, Shift 1Q82The total number of molecular orbitals formed from 2s and 2p atomic orbitals of a diatomic molecule is ________.
Idea: LCAO and MO Formation
New ideaEasyNumerical value - 31 Jan, Shift 1Q61The linear combination of atomic orbitals to form molecular orbitals takes place only when the combining atomic orbitals A. have the same…
Idea: LCAO and MO Formation
New ideaEasyOther
JEE Main 20232 questions in 2 shifts
- 12 Apr, Shift 1Q62The bond order and magnetic property of acetylide ion are same as that of
Idea: Isoelectronic Species Principle in MOT
New ideaMediumSingle correct - 13 Apr, Shift 1Q62In which of the following processes, the bond order increases and paramagnetic character changes to diamagnetic one ?
Idea: Magnetic Property Prediction
Asked the year beforeMediumSingle correct
JEE Main 20229 questions in 9 shifts
- 25 Jul, Shift 1Q81Among the following species the number of species…
Idea: Magnetic Property Prediction
Asked the year beforeMediumNumerical value - 27 Jul, Shift 1Q85According to MO theory, number of species/ions from the following having identical bond order is__.…
Idea: Bond Order Calculation
Asked the year beforeMediumNumerical value - 27 Jul, Shift 2Q62Match **List - I** with **List - II**. List - I (A) (B) (C) (D)…
Idea: Bond Order Calculation
Asked the year beforeEasyMatch the list - 28 Jul, Shift 1Q83The number of paramagnetic species among the following is __________.…
Idea: Magnetic Property Prediction
Asked the year beforeMediumNumerical value - 30 Jul, Shift 2Q52On the basis of MO. theory, the number of molecules from the following which have bond order two, is ________. ,…
Idea: Bond Order Calculation
Asked the year beforeMediumNumerical value - 24 Jun, Shift 2Q63The correct order of bond orders of C, N and O is, respectively
Idea: Bond Order Calculation
Asked the year beforeMediumSingle correct - 25 Jun, Shift 1Q61Bonding in which of the following diatomic molecule(s) become(s) stronger, on the basis of MO Theory, by removal of an electron ? (A)…
Idea: Bond Order Calculation
Asked the year beforeMediumOther - 26 Jun, Shift 1Q64Consider the ions/molecule For increasing bond order the correct option is :
Idea: Oxygen Ion Series Comparison
Asked the year beforeEasySingle correct - 28 Jun, Shift 1Q89Number of complexes which will exhibit synergic bonding amongst, , and…
Idea: LUMO as Pi-Acceptor
New ideaMediumNumerical value
JEE Main 20218 questions in 8 shifts
- 4 Aug, Shift 1Q32Consider the following species Which set represents all paramagnetic species?
Idea: Magnetic Property Prediction
Asked the year beforeMediumSingle correct - 4 Aug, Shift 2Q54The bond order in is ________ . ( integer answer)
Idea: Bond Order Calculation
New ideaEasyNumerical value - 26 Aug, Shift 2Q32The bond order and magnetic behaviour of ion are, respectively :
Idea: Oxygen Ion Series Comparison
New ideaMediumSingle correct - 31 Aug, Shift 2Q54According to molecular orbital theory, the number of unpaired electron(s) in is __________.
Idea: Magnetic Property Prediction
Asked the year beforeEasyNumerical value - 25 Feb, Shift 1Q32According to molecular orbital theory, the species among the following that does not exist is :
Idea: Bond Order Calculation
New ideaMediumSingle correct - 26 Feb, Shift 2Q31Match List-I with List-II. List-I (Molecule) | List-II (Bond order) (a) | (i) 1 (b) | (ii) 2 (c)…
Idea: Bond Order Calculation
New ideaMediumMatch the list - 25 Jul, Shift 2Q31In the following the correct bond order sequence is :
Idea: Oxygen Ion Series Comparison
New ideaEasySingle correct - 18 Mar, Shift 1Q52AX is a covalent diatomic molecule where A and X are second row elements of periodic table. Based on Molecular orbital theory, the bond…
Idea: Bond Order Calculation
New ideaMediumNumerical value
JEE Main 20202 questions in 2 shifts
- 9 Jan, Shift 1Q27If the magnetic moment of a dioxygen species is 1.73 B.M, it may be :
Idea: Magnetic Property Prediction
Asked the year beforeMediumSingle correct - 3 Sep, Shift 1Q27Of the species, NO, , and , the one with minimum bond strength is :
Idea: Bond Stability Comparison
New ideaMediumSingle correct
JEE Main 20171 question in 1 shift
- 2 Apr (offline)Q42Which of the following species is **not** paramagnetic ?
Idea: Magnetic Property Prediction
EasySingle correct
Questions from the official JEE Main Paper 1 shifts published by NTA (CBSE for 2017). Questions NTA dropped are left out. Topic and idea tags, counts and notes are Lumi’s.