NEET UG · Chemistry · Coordination Compounds

Coordination Isomerism: NEET previous year questions

4 questions in ten years of NEET, in 3 of 10 papers. Pattern: Most years. Here is how it is asked and which ideas come back.

Asked in 10 years: 4; about 0.4 per paper
Years asked: 3/10; last asked 2026
Chance of a question next paper: 50%; historical rate, how we compute it
Weighted estimate: 0.6; model; history: 0.4 a paper on average, typically 0–1

Key findings

01
Asked in 3 of 10 papers, 4 questions in all: #157 of 204 topics by ten-year total. It comes back every 4.0 years on average.
02
100% of its questions since 2018 tested an idea never asked before; none repeated an idea from the year before.
03
No idea in this topic has been asked twice: every question tested something new.
04
NEET has asked 4 of the 84 ideas in this topic; 76 have never been asked, directly or indirectly.
05
Mostly asked as one-line MCQ (50%); 75% easy, 0% hard, and up from 0.1 to 1.0 questions a paper since 2024.

Questions per year

Up to 2023: 0.1; per paper
Since 2024: 1.0; +0.8
Usual gap: 4.0 yrs; between papers asking it
Swing: ±0.7; questions, year to year

How it is asked

Difficulty, format and skill

Across all 4 questions on Coordination Isomerism since 2017.

Difficulty

QUESTIONS

Easy3 · 75%
Medium1 · 25%
Hard0 · 0%

Format

One-line MCQ · 2 Q50%
Two statements · 1 Q25%
Match the lists · 1 Q25%

Skill tested

Application · 3 Q75%
Recall · 1 Q25%

Repeats

New idea, or one asked before?

Each column is a paper. Blue questions tested an idea NEET had not asked before; navy ones went back to an idea from an earlier paper. 2017 is the first paper, so everything in it counts as new.

’17’18’19’20’21’22’23’24’25’26

Idea asked for the first time
Idea asked in an earlier paper

Coverage of the topic

NEET has asked 4 of the 84 ideas in this topic. 76 have never been asked yet.

Asked directly4 · 5%
Touched inside another question4 · 5%
Never asked76 · 90%

Ideas come from Lumi’s syllabus map of NCERT. A never-asked idea is not a safe skip: most new questions come from exactly these.

Drill down

Idea, year, question

Every idea NEET tested in this topic, with its ten papers. Open one to read the questions.

ideaAskedShareYears’17’18’19’20’21’22’23’24’25’26

1 · 25%25%1/10
- 2026 · Q78
  The complex which has facial and meridional isomers is (Given : py = pyridine and en = $\mathrm{H_2N-CH_2-CH_2-NH_2}$ )
  easyOne-line MCQNew idea
1 · 25%25%1/10
1 · 25%25%1/10
1 · 25%25%1/10

Squares are the ten papers, 2017 to 2026; darker means more questions. Share is of the level above.

Ideas

Every idea inside this topic

4 different ideas were tested; none came more than once. Geometric Isomerism in CN6 is the foundation for 45 other ideas in the syllabus.

Facial and Meridional Isomerism in [MA3B3]1×
identify complex showing an isomerism
One-line MCQ · 6% next
Optical Activity in [M(AA)2B2] Cis/Trans Isomers1×
statement i/ii on chirality of complexes
Two statements · 6% next · foundation for 2
Structural Isomerism Identification1×
match list on complexes and isomerism type
Match the lists · 6% next · foundation for 24
Geometric Isomerism in CN61×
identify type of isomerism in complex
One-line MCQ · 4% next · foundation for 45

Idea	Times	Format	Chance next	Foundation for
Facial and Meridional Isomerism in [MA3B3]identify complex showing an isomerism	1	One-line MCQApplication	6%	–
Optical Activity in [M(AA)2B2] Cis/Trans Isomersstatement i/ii on chirality of complexes	1	Two statementsApplication	6%	2 ideas
Structural Isomerism Identificationmatch list on complexes and isomerism type	1	Match the listsRecall	6%	24 ideas
Geometric Isomerism in CN6identify type of isomerism in complex	1	One-line MCQApplication	4%	45 ideas

Chance next is the historical rate at which an idea with this record came back in the following paper. It is low for every idea, which is why learning the topic beats memorising past questions. All repeated ideas

Every question

Coordination Isomerism questions, year by year

The opening words of each question as it appeared in the official paper, with the idea it tested.

NEET 20262 questions

Q47
Given below are two statements: Statement-I : $[\mathrm{Fe(ox)_3}]^{3-}$ is chiral. Statement-II : trans- $[\mathrm{Cr(H_2O)_2(ox)_2}]^-$ …
Idea: Optical Activity in [M(AA)2B2] Cis/Trans Isomers
New ideaMediumTwo statements
Q78
The complex which has facial and meridional isomers is (Given : py = pyridine and en = $\mathrm{H_2N-CH_2-CH_2-NH_2}$ )
Idea: Facial and Meridional Isomerism in [MA3B3]
New ideaEasyOne-line MCQ

NEET 20241 question

Q82
Match List I with List II. List I (Complex) | List II (Type of isomerism) A. $[\mathrm{Co(NH_3)_5(NO_2)}]\mathrm{Cl_2}$ | I. Solvate…
Idea: Structural Isomerism Identification
New ideaEasyMatch the lists

NEET 20181 question

Q72
The type of isomerism shown by the complex $\mathrm{[CoCl_2(en)_2]}$ is
Idea: Geometric Isomerism in CN6
New ideaEasyOne-line MCQ

Questions from the official NEET UG papers published by NTA (CBSE before 2019). Topic and idea tags, counts and notes are Lumi’s.