NEET UG · Chemistry · Thermodynamics

Gibbs Free Energy: NEET previous year questions

7 questions in ten years of NEET, in 6 of 10 papers. Pattern: Every year. Here is how it is asked and which ideas come back.

Asked in 10 years: 7; about 0.7 per paper
Years asked: 6/10; last asked 2026
Chance of a question next paper: 64%; historical rate, how we compute it
Weighted estimate: 0.8; model; history: 0.7 a paper on average, typically 0–1

Key findings

01
Asked in 6 of 10 papers, 7 questions in all: #117 of 204 topics by ten-year total. It comes back every 1.8 years on average.
02
67% of its questions since 2018 tested an idea never asked before; 1 repeated an idea from the year before.
03
The most repeated idea is Entropy Change Prediction, asked 3 times (2019, 2020, 2024), usually as “signs of enthalpy and entropy change”.
04
NEET has asked 5 of the 75 ideas in this topic; 62 have never been asked, directly or indirectly.
05
Mostly asked as numerical (43%); 57% easy, 0% hard, and up from 0.6 to 1.0 questions a paper since 2024.

Questions per year

Up to 2023: 0.6; per paper
Since 2024: 1.0; +0.4
Usual gap: 1.8 yrs; between papers asking it
Swing: ±0.6; questions, year to year

How it is asked

Difficulty, format and skill

Across all 7 questions on Gibbs Free Energy since 2017.

Difficulty

QUESTIONS

Easy4 · 57%
Medium3 · 43%
Hard0 · 0%

Format

Numerical · 3 Q43%
One-line MCQ · 3 Q43%
Other · 1 Q14%

Skill tested

Calculation · 3 Q43%
Concept · 3 Q43%
Application · 1 Q14%

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 5 of the 75 ideas in this topic. 62 have never been asked yet.

862

Asked directly5 · 7%
Touched inside another question8 · 11%
Never asked62 · 83%

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

Repeated3 · 43%43%3/10
- 2024 · Q61
  In which of the following processes entropy increases? A. A liquid evaporates to vapour. B. Temperature of a crystalline solid lowered…
  easyOther
- 2020 · Q127
  For the reaction, $\mathrm{2Cl(g) \to Cl_2(g)}$ , the correct option is :
  easyOne-line MCQAsked the year before
- 2019 · Q86
  In which case change in entropy is negative ?
  easyOne-line MCQNew idea
1 · 14%14%1/10
1 · 14%14%1/10
1 · 14%14%1/10
1 · 14%14%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

5 different ideas were tested; 1 came more than once. Entropy Change Prediction is the foundation for 40 other ideas in the syllabus.

Entropy Change Prediction3×
signs of enthalpy and entropy change
One-line MCQ · 6% next · foundation for 40
Entropy of Free Expansion1×
numerical
Numerical · 6% next
Gibbs Energy and Equilibrium1×
numerical
Numerical · 6% next · foundation for 9
Entropy of Isothermal Gas Expansion1×
identify thermodynamic quantities for process
One-line MCQ · 4% next · foundation for 4
Temperature of Spontaneity1×
numerical
Numerical · 4% next · foundation for 1

Idea	Times	Format	Chance next	Foundation for
Entropy Change Predictionsigns of enthalpy and entropy change	3	One-line MCQConcept	6%	40 ideas
Entropy of Free Expansionnumerical	1	NumericalCalculation	6%	–
Gibbs Energy and Equilibriumnumerical	1	NumericalCalculation	6%	9 ideas
Entropy of Isothermal Gas Expansionidentify thermodynamic quantities for process	1	One-line MCQConcept	4%	4 ideas
Temperature of Spontaneitynumerical	1	NumericalCalculation	4%	1 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

Gibbs Free Energy 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

Q59
Two moles of an ideal gas undergo free expansion from 10 L to 100 L at 300 K. The values of $\Delta S_{system}$ and…
Idea: Entropy of Free Expansion
New ideaMediumNumerical
Q74
A protein undergoes reversible thermal denaturation from its initial state N to denatured state D according to N $\rightleftharpoons$ D.…
Idea: Gibbs Energy and Equilibrium
New ideaMediumNumerical

NEET 20241 question

Q61
In which of the following processes entropy increases? A. A liquid evaporates to vapour. B. Temperature of a crystalline solid lowered…
Idea: Entropy Change Prediction
EasyOther

NEET 20211 question

Q96
For irreversible expansion of an ideal gas under isothermal condition, the correct option is :
Idea: Entropy of Isothermal Gas Expansion
New ideaMediumOne-line MCQ

NEET 20201 question

Q127
For the reaction, $\mathrm{2Cl(g) \to Cl_2(g)}$ , the correct option is :
Idea: Entropy Change Prediction
Asked last yearEasyOne-line MCQ

NEET 20191 question

Q86
In which case change in entropy is negative ?
Idea: Entropy Change Prediction
New ideaEasyOne-line MCQ

NEET 20171 question

Q77
For a given reaction, $\Delta H$ = 35.5 kJ $\mathrm{mol^{-1}}$ and $\Delta S$ = 83.6 J $\mathrm{K^{-1}}$ $\mathrm{mol^{-1}}$ . The reaction…
Idea: Temperature of Spontaneity
EasyNumerical

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