JEE Main · Physics · Thermodynamics
First Law of Thermodynamics: JEE Main previous year questions
40 questions in the 108 JEE Main shifts Lumi analysed, in 8 of 8 years. Pattern: Asked most years. 17 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 40
- in 36 of 108 shifts
- Years asked
- 8/8
- last asked 2026
- Weighted estimate
- 0.4
- model; history: 0.4 a shift on average, typically 0.2–0.8
Key findings
- 01
Asked in 8 of 8 years with analysed shifts and in 36 of 108 shifts: 40 questions, #81 of 196 topics. It came in every year with analysed shifts.
- 02
54% of its questions since 2020 tested an idea no earlier year had asked; 7 repeated an idea from the year before.
- 03
The most repeated idea is Heat in Isochoric and Isobaric Processes, asked 5 times in 5 shifts (2021, 2022, 2024, 2026), most often as “heat supplied in isobaric heating”.
- 04
JEE Main has asked 21 of the 54 ideas in this topic; 28 have never been asked, directly or inside another question.
- 05
Mostly asked as single correct (50%); 35% need a numerical answer, 50% are easy and 8% hard.
- 06
The skill tested most is calculation (48%), then multi-step (33%).
Questions a shift, year by year
Out of the 25 Physics 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: 7 in 24 shifts · 2022: 9 in 24 shifts · 2023: 4 in 12 shifts · 2024: 8 in 18 shifts · 2025: 2 in 8 shifts · 2026: 7 in 9 shifts.
- Up to 2023
- 0.4
- a shift, of 25
- Since 2024
- 0.5
- 0.1
- Usual gap
- 1.3 yrs
- between years asking it
- Shifts with it
- 36/108
- 33% of analysed shifts
Revise first
- Mayer's Relation (Cp and Cv) · asked 2017, 2024, 2026
- Heat in Isochoric and Isobaric Processes · asked 2021, 2022, 2024, 2026
- Internal Energy Calculation · asked 2021, 2022, 2024, 2026
How it is asked
Difficulty, format and skill
Across all 40 questions on First Law of Thermodynamics since 2017.
Difficulty
QUESTIONS- Easy20 · 50%
- Medium17 · 43%
- Hard3 · 8%
Format
SHARE- Single correct · 20 Q50%
- Numerical value · 14 Q35%
- Diagram based · 4 Q10%
- Other · 1 Q3%
- Two statements · 1 Q3%
Skill tested
SHARE- Calculation · 19 Q48%
- Multi-step · 13 Q33%
- Data or graph · 3 Q8%
- Application · 3 Q8%
- Conceptual · 2 Q5%
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 21 of the 54 ideas in this topic. 28 have never been asked yet.
- Asked directly21 · 39%
- Touched inside another question5 · 9%
- Never asked28 · 52%
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.
19 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
21 different ideas were tested; 10 came more than once.
heat supplied in isobaric heating
Single correct · 5 shifts · 1 numericaltemperature of mixture of two gases
Single correct · 4 shiftsheat supplied to gas against spring piston
Numerical value · 4 shifts · 3 numericalchange in internal energy at constant volume
Single correct · 3 shifts · 1 numericalwork done from heat and temperature rise of helium
Single correct · 3 shiftswork in isothermal compression from bulk modulus
Numerical value · 2 shifts · 2 numericalfinal pressure after sudden adiabatic compression
Single correct · 2 shiftsinternal energy change in boiling at constant pressure
Numerical value · 2 shifts · 1 numericalmolar heat capacity of process
Numerical value · 2 shifts · 2 numericalwork from p-v graph area
Diagram based · 2 shifts · 1 numericalwork in adiabatic expansion from given data
Numerical value · 1 shift · 1 numericalcount correct statements on thermodynamics basics
Other · 1 shiftchange in internal energy in adiabatic expansion
Single correct · 1 shifttemperature change in adiabatic compression
Single correct · 1 shiftheat given in isobaric expansion of diatomic gas
Single correct · 1 shiftwork in cyclic process from p-v loop area
Diagram based · 1 shifttrue or false statements on heat and work
Two statements · 1 shiftheat absorbed at constant pressure
Numerical value · 1 shift · 1 numericalwork in a segment of a cyclic process
Diagram based · 1 shiftfinal temperature on joining insulated gas vessels
Single correct · 1 shiftfinal temperature after energy conversion
Numerical value · 1 shift · 1 numerical
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Heat in Isochoric and Isobaric Processesheat supplied in isobaric heating | 5 | 5 | Single correctCalculation | 1 | |
| Internal Energy Calculationtemperature of mixture of two gases | 4 | 4 | Single correctCalculation | – | |
| Work and Heat in Isothermal Processesheat supplied to gas against spring piston | 4 | 4 | Numerical valueCalculation | 3 | |
| Mayer's Relation (Cp and Cv)change in internal energy at constant volume | 3 | 3 | Single correctMulti-step | 1 | |
| First Law Energy Balancework done from heat and temperature rise of helium | 3 | 3 | Single correctCalculation | – | |
| Isothermal Bulk Moduluswork in isothermal compression from bulk modulus | 2 | 2 | Numerical valueMulti-step | 2 | |
| Adiabatic P-V Relationfinal pressure after sudden adiabatic compression | 2 | 2 | Single correctApplication | – | |
| First Law in Phase Transitionsinternal energy change in boiling at constant pressure | 2 | 2 | Numerical valueCalculation | 1 | |
| Molar Heat Capacity in Polytropic Processesmolar heat capacity of process | 2 | 2 | Numerical valueCalculation | 2 | |
| Work Done from P-V Graph Areawork from p-v graph area | 2 | 2 | Diagram basedCalculation | 1 | |
| Adiabatic Work Formulawork in adiabatic expansion from given data | 1 | 1 | Numerical valueMulti-step | 1 | |
| State vs. Path Functionscount correct statements on thermodynamics basics | 1 | 1 | OtherConceptual | – | |
| Work and Internal Energy in Adiabatic Processeschange in internal energy in adiabatic expansion | 1 | 1 | Single correctMulti-step | – | |
| Adiabatic T-V Relationtemperature change in adiabatic compression | 1 | 1 | Single correctCalculation | – | |
| Fraction of Heat Converted to Work (Isobaric)heat given in isobaric expansion of diatomic gas | 1 | 1 | Single correctCalculation | – | |
| Work from P-V Loop Areawork in cyclic process from p-v loop area | 1 | 1 | Diagram basedData or graph | – | |
| Thermodynamic Sign Conventionstrue or false statements on heat and work | 1 | 1 | Two statementsConceptual | – | |
| Degrees of Freedomheat absorbed at constant pressure | 1 | 1 | Numerical valueCalculation | 1 | |
| First Law in Cyclic Processeswork in a segment of a cyclic process | 1 | 1 | Diagram basedMulti-step | – | |
| Free Expansion of Ideal Gasfinal temperature on joining insulated gas vessels | 1 | 1 | Single correctMulti-step | – | |
| Mechanical Energy to Internal Energy Conversionfinal temperature after energy conversion | 1 | 1 | Numerical valueMulti-step | 1 |
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
First Law of Thermodynamics 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 20267 questions in 6 shifts
- 2 Apr, Shift 1Q47A vessel contains of a gas at pressure bar and temperature C with and . It is…
Idea: Adiabatic Work Formula
New ideaMediumNumerical value - 2 Apr, Shift 2Q485 moles of unknown gas is heated at constant volume from 10°C to 20°C. The molar specific heat of this gas at constant pressure …
Idea: Mayer's Relation (Cp and Cv)
MediumNumerical value - 5 Apr, Shift 1Q33Consider the following statements: A. Zeroth law of thermodynamics gives concept of temperature B. First law of thermodynamics gives…
Idea: State vs. Path Functions
New ideaMediumOther - 6 Apr, Shift 1Q50A certain gas is isothermally compressed to of its initial volume ( litre) by applying…
Idea: Isothermal Bulk Modulus
MediumNumerical value - 6 Apr, Shift 2Q35If 2 mole of an ideal monoatomic gas at temperature , is mixed with 6 mole of another ideal monoatomic gas at temperature then the…
Idea: Internal Energy Calculation
EasySingle correct - 8 Apr, Shift 2Q35One mole of diatomic gas having rotational modes only is kept in a cylinder with a piston system. The cross-section area of the cylinder…
Idea: Heat in Isochoric and Isobaric Processes
MediumSingle correct - 8 Apr, Shift 2Q36Initial pressure and volume of a monoatomic ideal gas are and . The change in internal energy of this gas in adiabatic expansion to…
Idea: Work and Internal Energy in Adiabatic Processes
New ideaMediumSingle correct
JEE Main 20252 questions in 1 shift
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Idea: Adiabatic T-V Relation
New ideaEasySingle correct - 3 Apr, Shift 1Q35A piston of mass M is hung from a massless spring whose restoring force law goes as , where k is the spring constant of…
Idea: Work and Heat in Isothermal Processes
Asked the year beforeHardDiagram based · figure
JEE Main 20248 questions in 8 shifts
- 4 Apr, Shift 2Q83Three moles of an ideal gas are compressed isothermally from 60 L to 20 L using constant pressure of 5 atm. Heat exchange Q for the…
Idea: Work and Heat in Isothermal Processes
EasyNumerical value - 5 Apr, Shift 1Q38The heat absorbed by a system in going through the given cyclic process is :
Idea: Work from P-V Loop Area
New ideaMediumDiagram based · figure - 6 Apr, Shift 1Q36The specific heat at constant pressure of a real gas obeying equation is:
Idea: Mayer's Relation (Cp and Cv)
HardSingle correct - 6 Apr, Shift 2Q39A total of 48 J heat is given to one mole of helium kept in a cylinder. The temperature of helium increases by . The…
Idea: First Law Energy Balance
Asked the year beforeEasySingle correct - 8 Apr, Shift 1Q37Two different adiabatic paths for the same gas intersect two isothermal curves as shown in P-V diagram. The relation between the ratio…
Idea: Adiabatic P-V Relation
Asked the year beforeMediumSingle correct · figure - 8 Apr, Shift 2Q38A diatomic gas () does 100 J of work in an isobaric expansion. The heat given to the gas is :
Idea: Fraction of Heat Converted to Work (Isobaric)
New ideaEasySingle correct - 1 Feb, Shift 2Q38A diatomic gas () does 200 J of work when it is expanded isobarically. The heat given to the gas in the process is :
Idea: Heat in Isochoric and Isobaric Processes
EasySingle correct - 27 Jan, Shift 1Q380.08 kg air is heated at constant volume through 5°C. The specific heat of air at constant volume is 0.17 kcal/kg°C and J = 4.18…
Idea: Internal Energy Calculation
EasySingle correct
JEE Main 20234 questions in 4 shifts
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Idea: First Law Energy Balance
EasySingle correct - 8 Apr, Shift 1Q33Given below are two statements: Statement I: If heat is added to a system, its temperature must increase. Statement II: If positive work…
Idea: Thermodynamic Sign Conventions
New ideaMediumTwo statements - 11 Apr, Shift 1Q441 kg of water at C is converted into steam at C by boiling at atmospheric pressure. The volume of water changes from…
Idea: First Law in Phase Transitions
MediumSingle correct - 13 Apr, Shift 2Q38The initial pressure and volume of an ideal gas are and . The final pressure of the gas when the gas is suddenly compressed to…
Idea: Adiabatic P-V Relation
New ideaEasySingle correct
JEE Main 20229 questions in 8 shifts
- 26 Jul, Shift 1Q437 mol of a certain monoatomic ideal gas undergoes a temperature increase of 40K at constant pressure. The increase in the internal energy…
Idea: Internal Energy Calculation
Asked the year beforeEasySingle correct - 28 Jul, Shift 2Q24At a certain temperature, the degrees of freedom per molecule for gas is 8. The gas performs 150 J of work when it expands under constant…
Idea: Degrees of Freedom
New ideaEasyNumerical value - 29 Jul, Shift 2Q47A thermodynamic system is taken from an original state D to an intermediate state E by the linear process shown in the figure. Its volume…
Idea: Work Done from P-V Graph Area
EasyDiagram based · figure - 24 Jun, Shift 2Q59A monoatomic gas performs a work of where Q is the heat supplied to it. The molar heat capacity of the gas will be ________R…
Idea: Molar Heat Capacity in Polytropic Processes
Asked the year beforeMediumNumerical value - 27 Jun, Shift 2Q53A diatomic gas ( = 1.4) does 400J of work when it is expanded isobarically. The heat given to the gas in the process is __________…
Idea: Heat in Isochoric and Isobaric Processes
Asked the year beforeEasyNumerical value - 27 Jun, Shift 2Q84When 5 moles of He gas expand isothermally and reversibly at 300 K from 10 litre to 20 litre, the magnitude of the maximum work obtained…
Idea: Work and Heat in Isothermal Processes
New ideaEasyNumerical value - 28 Jun, Shift 2Q38A sample of an ideal gas is taken through the cyclic process ABCA as shown in figure. It absorbs, 40 J of heat during the part AB, no heat…
Idea: First Law in Cyclic Processes
New ideaMediumDiagram based · figure - 29 Jun, Shift 1Q35A cylinder of fixed capacity of 44.8 litres contains helium gas at standard temperature and pressure. The amount of heat needed to raise…
Idea: Heat in Isochoric and Isobaric Processes
Asked the year beforeEasySingle correct - 30 Jun, Shift 1Q831.0 mol of monoatomic ideal gas is expanded from state 1 to state 2 as shown in the figure. The magnitude of the work done for the…
Idea: Work and Heat in Isothermal Processes
New ideaMediumNumerical value · figure
JEE Main 20217 questions in 6 shifts
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Idea: Internal Energy Calculation
New ideaMediumSingle correct - 4 Aug, Shift 1Q251 g of water at 100°C is converted into steam at the same temperature and at 1 atmospheric pressure. The change in internal energy is…
Idea: First Law in Phase Transitions
New ideaEasyNumerical value - 4 Aug, Shift 1Q53A lead bullet weighing 18 g and travelling with a velocity of 500 m/s is embedded in a wooden block weighing 1 kg. If both the…
Idea: Mechanical Energy to Internal Energy Conversion
New ideaMediumNumerical value - 4 Aug, Shift 2Q12Consider two thermally insulated vessels filled with air, having volumes (), (), Pressure ,…
Idea: Free Expansion of Ideal Gas
New ideaMediumSingle correct - 26 Aug, Shift 1Q4An electric appliance supplies 6000 J/min heat to the system. If the system delivers a power of 90 W. How long it would take to increase…
Idea: First Law Energy Balance
New ideaEasySingle correct - 25 Feb, Shift 1Q18A diatomic gas, having and , is heated at constant pressure. The ratio dU : dQ : dW :
Idea: Heat in Isochoric and Isobaric Processes
New ideaEasySingle correct - 26 Feb, Shift 2Q271 mole of rigid diatomic gas performs a work of when heat Q is supplied to it. The molar heat capacity of the gas during…
Idea: Molar Heat Capacity in Polytropic Processes
New ideaMediumNumerical value
JEE Main 20202 questions in 2 shifts
- 8 Jan, Shift 1Q47The magnitude of work done by a gas that undergoes a reversible expansion along the path ABC shown in the figure is ______.
Idea: Work Done from P-V Graph Area
New ideaEasyNumerical value · figure - 4 Sep, Shift 2Q22The change in the magnitude of the volume of an ideal gas when a small additional pressure is applied at a constant…
Idea: Isothermal Bulk Modulus
New ideaHardNumerical value
JEE Main 20171 question in 1 shift
- 2 Apr (offline)Q10and are specific heats at constant pressure and constant volume respectively. It is observed that for hydrogen…
Idea: Mayer's Relation (Cp and Cv)
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.