NEET UG · Chemistry · Organic Chemistry - Some Basic Principles and Techniques

Purification, Analysis and Isomerism of Organic Compounds: NEET previous year questions

11 questions in ten years of NEET, in 8 of 10 papers. Pattern: Every year. Here is how it is asked and which ideas come back.

Asked in 10 years: 11; about 1.1 per paper
Years asked: 8/10; last asked 2026
Chance of a question next paper: 84%; historical rate, how we compute it
Weighted estimate: 1.3; model; history: 1.1 a paper on average, typically 0–2

Key findings

01
Asked in 8 of 10 papers, 11 questions in all: #61 of 204 topics by ten-year total. It comes back every 1.3 years on average.
02
78% of its questions since 2018 tested an idea never asked before; none repeated an idea from the year before.
03
The most repeated idea is Lassaigne's Test for N and Halogens, asked 2 times (2023, 2025), usually as “identify compound giving test”.
04
NEET has asked 0 of the 9 ideas in this topic; 0 have never been asked, directly or indirectly.
05
Mostly asked as one-line MCQ (91%); 55% easy, 9% hard, and up from 0.8 to 1.6 questions a paper since 2024.

Questions per year

Up to 2023: 0.8; per paper
Since 2024: 1.6; +0.8
Usual gap: 1.3 yrs; between papers asking it
Swing: ±0.8; questions, year to year

Recent framings

identify compound giving test
match list on separation methods
count isomers of given formula

Revise first

Lassaigne's Test for N and Halogens (2023 2025); Lassaigne's Test for Sulphur (2026); Types of Distillation (2017 2025)

How it is asked

Difficulty, format and skill

Across all 11 questions on Purification, Analysis and Isomerism of Organic Compounds since 2017.

Difficulty

QUESTIONS

641

Easy6 · 55%
Medium4 · 36%
Hard1 · 9%

Format

One-line MCQ · 10 Q91%
Match the lists · 1 Q9%

Skill tested

Recall · 8 Q73%
Application · 2 Q18%
Multi-step · 1 Q9%

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 0 of the 9 ideas in this topic. 0 have never been asked yet.

Asked directly0 · 0%
Touched inside another question9 · 100%
Never asked0 · 0%

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

Repeated2 · 18%18%2/10
- 2025 · Q90
  Which one of the following reactions does NOT belong to “Lassaigne's test”?
  easyOne-line MCQ
- 2023 · Q54
  In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with Fe $^{3+}$ due to…
  mediumOne-line MCQNew idea
Repeated2 · 18%18%2/10
1 · 9%9%1/10
1 · 9%9%1/10
1 · 9%9%1/10
1 · 9%9%1/10
1 · 9%9%1/10
1 · 9%9%1/10
1 · 9%9%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

9 different ideas were tested; 2 came more than once.

Lassaigne's Test for N and Halogens2×
identify compound giving test
One-line MCQ · 6% next
Types of Distillation2×
choose separation method for isomers
Match the lists · 6% next
Lassaigne's Test for Sulphur1×
identify compound giving test
One-line MCQ · 6% next
Counting Isomers1×
count isomers of given formula
One-line MCQ · 6% next
Purification Techniques1×
identify technique by principle
One-line MCQ · 6% next
Kjeldahl Method1×
identify compound suited to analytical method
One-line MCQ · 4% next
Types of Structural Isomerism1×
identify compound showing isomerism type
One-line MCQ · 4% next
Chromatography1×
classify technique by type
One-line MCQ · 4% next
Electrophiles and Nucleophiles1×
true statement selection on electrophile
One-line MCQ · 4% next

Idea	Times	Format	Chance next	Foundation for
Lassaigne's Test for N and Halogensidentify compound giving test	2	One-line MCQRecall	6%	–
Types of Distillationchoose separation method for isomers	2	Match the listsApplication	6%	–
Lassaigne's Test for Sulphuridentify compound giving test	1	One-line MCQRecall	6%	–
Counting Isomerscount isomers of given formula	1	One-line MCQMulti-step	6%	–
Purification Techniquesidentify technique by principle	1	One-line MCQRecall	6%	–
Kjeldahl Methodidentify compound suited to analytical method	1	One-line MCQRecall	4%	–
Types of Structural Isomerismidentify compound showing isomerism type	1	One-line MCQApplication	4%	–
Chromatographyclassify technique by type	1	One-line MCQRecall	4%	–
Electrophiles and Nucleophilestrue statement selection on electrophile	1	One-line MCQRecall	4%	–

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

Purification, Analysis and Isomerism of Organic Compounds questions, year by year

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

NEET 20261 question

Q55
The amino acid that gives a red-blood colour on treating its sodium fusion extract with sodium nitroprusside is
Idea: Lassaigne's Test for Sulphur
New ideaMediumOne-line MCQ

NEET 20253 questions

Q72
Match List I with List II List I (Mixture) | List II (Method of Separation) A. $CHCl_3 + C_6H_5NH_2$ | I. Distillation under reduced…
Idea: Types of Distillation
EasyMatch the lists
Q86
Total number of possible isomers (both structural as well as stereoisomers) of cyclic ethers of molecular formula $C_4H_8O$ is :
Idea: Counting Isomers
New ideaHardOne-line MCQ
Q90
Which one of the following reactions does NOT belong to “Lassaigne's test”?
Idea: Lassaigne's Test for N and Halogens
EasyOne-line MCQ

NEET 20241 question

Q83
On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the…
Idea: Purification Techniques
New ideaEasyOne-line MCQ

NEET 20231 question

Q54
In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with Fe $^{3+}$ due to…
Idea: Lassaigne's Test for N and Halogens
New ideaMediumOne-line MCQ

NEET 20221 question

Q55
The Kjeldahl's method for the estimation of nitrogen can be used to estimate the amount of nitrogen in which one of the following…
Idea: Kjeldahl Method
New ideaMediumOne-line MCQ · figure

NEET 20211 question

Q53
The compound which shows metamerism is :
Idea: Types of Structural Isomerism
New ideaMediumOne-line MCQ

NEET 20201 question

Q108
Paper chromatography is an example of :
Idea: Chromatography
New ideaEasyOne-line MCQ

NEET 20172 questions

Q70
The correct statement regarding electrophile is :
Idea: Electrophiles and Nucleophiles
EasyOne-line MCQ
Q78
The most suitable method of separation of 1 : 1 mixture of ortho and para - nitrophenols is :
Idea: Types of Distillation
EasyOne-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.