JEE Main · Chemistry · Thermodynamics (Chemistry)
Entropy: JEE Main previous year questions
4 questions in the 108 JEE Main shifts Lumi analysed, in 3 of 8 years. Pattern: Comes in cycles. 0 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 4
- in 4 of 108 shifts
- Years asked
- 3/8
- last asked 2023
- Weighted estimate
- 0.0
- model; history: 0.0 a shift on average, typically 0.0–0.1
Key findings
- 01
Asked in 3 of 8 years with analysed shifts and in 4 of 108 shifts: 4 questions, #193 of 196 topics. The years that asked it were 1.5 apart on average. Last asked in 2023.
- 02
100% of its questions since 2020 tested an idea no earlier year had asked; none repeated an idea from the year before.
- 03
No idea in this topic has been asked twice: every question tested something new.
- 04
JEE Main has asked 4 of the 50 ideas in this topic; 41 have never been asked, directly or inside another question.
- 05
Mostly asked as numerical value (50%); 50% need a numerical answer, 50% are easy and 0% hard.
- 06
The skill tested most is calculation (50%), then conceptual (50%).
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: 0 in 1 shift · 2020: 1 in 12 shifts · 2021: 1 in 24 shifts · 2022: 0 in 24 shifts · 2023: 2 in 12 shifts · 2024: 0 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.
- Up to 2023
- 0.1
- a shift, of 25
- Since 2024
- 0.0
- -0.1
- Usual gap
- 1.5 yrs
- between years asking it
- Shifts with it
- 4/108
- 4% of analysed shifts
How it is asked
Difficulty, format and skill
Across all 4 questions on Entropy since 2017.
Difficulty
QUESTIONS- Easy2 · 50%
- Medium2 · 50%
- Hard0 · 0%
Format
SHARE- Numerical value · 2 Q50%
- Single correct · 1 Q25%
- Other · 1 Q25%
Skill tested
SHARE- Calculation · 2 Q50%
- Conceptual · 2 Q50%
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 4 of the 50 ideas in this topic. 41 have never been asked yet.
- Asked directly4 · 8%
- Touched inside another question5 · 10%
- Never asked41 · 82%
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
Idea, year, question
Every idea JEE Main tested in this topic, with its eight years. Open one to read the questions.
- 15 Apr ’23 S1 · Q8230.4 kJ of heat is required to melt one mole of sodium chloride and the entropy change at the melting point is 28.4 J…
easyNumerical valueNew idea
- 15 Apr ’23 S1 · Q82
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
4 different ideas were tested; none came more than once.
melting point from entropy of fusion
Numerical value · 1 shift · 1 numericalentropy change of surroundings isothermal expansion
Numerical value · 1 shift · 1 numericalprocesses with decrease in entropy
Other · 1 shifttrue statement selection on entropy
Single correct · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Entropy Change at Equilibrium Phase Transitionmelting point from entropy of fusion | 1 | 1 | Numerical valueCalculation | 1 | |
| Entropy of Surroundings and Universeentropy change of surroundings isothermal expansion | 1 | 1 | Numerical valueCalculation | 1 | |
| Predicting Entropy Signprocesses with decrease in entropy | 1 | 1 | OtherConceptual | – | |
| Temperature Dependence of Reaction Entropytrue statement selection on entropy | 1 | 1 | Single correctConceptual | – |
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
Entropy 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 20232 questions in 2 shifts
- 12 Apr, Shift 1Q83One mole of an ideal gas at 350K is in a 2.0 L vessel of thermally conducting walls, which are in contact with the surroundings. It…
Idea: Entropy of Surroundings and Universe
New ideaMediumNumerical value - 15 Apr, Shift 1Q8230.4 kJ of heat is required to melt one mole of sodium chloride and the entropy change at the melting point is 28.4 J…
Idea: Entropy Change at Equilibrium Phase Transition
New ideaEasyNumerical value
JEE Main 20211 question in 1 shift
- 17 Mar, Shift 2Q32During which of the following processes, does entropy decrease ? (A) Freezing of water to ice at (B) Freezing of water…
Idea: Predicting Entropy Sign
New ideaMediumOther
JEE Main 20201 question in 1 shift
- 9 Jan, Shift 2Q26The true statement amongst the following is :
Idea: Temperature Dependence of Reaction Entropy
New ideaEasySingle 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.