JEE Main · Chemistry · Some Basic Concepts of Chemistry
Stoichiometry: JEE Main previous year questions
81 questions in the 108 JEE Main shifts Lumi analysed, in 7 of 8 years. Pattern: Asked most years. 29 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 81
- in 59 of 108 shifts
- Years asked
- 7/8
- last asked 2026
- Weighted estimate
- 0.8
- model; history: 0.6 a shift on average, typically 0.4–0.9
Key findings
- 01
Asked in 7 of 8 years with analysed shifts and in 59 of 108 shifts: 81 questions, #17 of 196 topics.
- 02
37% of its questions since 2020 tested an idea no earlier year had asked; 32 repeated an idea from the year before.
- 03
The most repeated idea is Stoichiometry of Dumas Method, asked 10 times in 10 shifts (2020, 2021, 2022, 2025), most often as “percentage nitrogen by dumas method”.
- 04
JEE Main has asked 24 of the 56 ideas in this topic; 28 have never been asked, directly or inside another question.
- 05
Mostly asked as numerical value (68%); 68% need a numerical answer, 57% are easy and 2% hard. It went up from 0.5 to 1.0 questions a shift since 2024.
- 06
The skill tested most is calculation (84%), then multi-step (10%).
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: 5 in 12 shifts · 2021: 20 in 24 shifts · 2022: 21 in 24 shifts · 2023: 6 in 12 shifts · 2024: 8 in 18 shifts · 2025: 13 in 8 shifts · 2026: 8 in 9 shifts.
- Up to 2023
- 0.5
- a shift, of 25
- Since 2024
- 1.0
- +0.5
- Usual gap
- 1.0 yrs
- between years asking it
- Shifts with it
- 59/108
- 55% of analysed shifts
Recent framings
- numerical: residue mass on heating salt
- numerical: percentage of element by Carius method
- numerical: gas volume from impure reagent
Revise first
- Stoichiometry of Dumas Method · asked 2020, 2021, 2022, 2025
- Empirical Formula from Combustion Data · asked 2021, 2022, 2023, 2025
- Gravimetric Precipitation Analysis · asked 2021, 2022, 2023, 2025, 2026
How it is asked
Difficulty, format and skill
Across all 81 questions on Stoichiometry since 2017.
Difficulty
QUESTIONS- Easy46 · 57%
- Medium33 · 41%
- Hard2 · 2%
Format
SHARE- Numerical value · 55 Q68%
- Single correct · 23 Q28%
- Match the list · 1 Q1%
- Diagram based · 1 Q1%
- Other · 1 Q1%
Skill tested
SHARE- Calculation · 68 Q84%
- Multi-step · 8 Q10%
- Recall · 3 Q4%
- Conceptual · 1 Q1%
- Application · 1 Q1%
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 24 of the 56 ideas in this topic. 28 have never been asked yet.
- Asked directly24 · 43%
- Touched inside another question4 · 7%
- Never asked28 · 50%
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.
18 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
24 different ideas were tested; 13 came more than once.
percentage nitrogen by dumas method
Numerical value · 10 shifts · 7 numericalpercentage nitrogen by kjeldahl method
Numerical value · 9 shifts · 5 numericalproduct mass with limiting reagent
Numerical value · 8 shifts · 4 numericalpercentages from combustion analysis
Numerical value · 8 shifts · 5 numericalpercentage yield of product
Numerical value · 7 shifts · 7 numericalpercentage halogen by carius method
Numerical value · 6 shifts · 6 numericalmoles of reactant from product mass
Numerical value · 5 shifts · 3 numericalproduct mass from combustion of hydrocarbon
Numerical value · 4 shifts · 2 numericalsample mass from combustion analysis
Numerical value · 3 shifts · 2 numericalmass of reactant from gas volume
Numerical value · 3 shifts · 2 numericalmass of reactant from product mass
Numerical value · 3 shifts · 2 numericalresidue mass on heating salt
Numerical value · 2 shifts · 1 numericalhydrocarbon formula from combustion volumes
Numerical value · 2 shifts · 2 numericalmass of product from reactant mass
Single correct · 1 shiftmass of precipitate from organic product
Numerical value · 1 shift · 1 numericalproduct mass from impure reactant
Numerical value · 1 shift · 1 numericaloxygen needed for combustion
Single correct · 1 shiftcomposition of mixture from mass loss
Single correct · 1 shiftgas volume stoichiometry n2 and h2
Numerical value · 1 shift · 1 numericaloverall yield of two-step reaction
Numerical value · 1 shift · 1 numericalcount bridging atoms in product of reaction sequence
Single correct · 1 shiftpercentage of carbonate from two-stage titration
Numerical value · 1 shift · 1 numericaloverall yield of sequential reactions
Numerical value · 1 shift · 1 numericalreactant mass from product and yield
Numerical value · 1 shift · 1 numerical
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Stoichiometry of Dumas Methodpercentage nitrogen by dumas method | 10 | 10 | Numerical valueCalculation | 7 | |
| Stoichiometry of Kjeldahl Methodpercentage nitrogen by kjeldahl method | 9 | 9 | Numerical valueCalculation | 5 | |
| Limiting Reagent Identificationproduct mass with limiting reagent | 8 | 8 | Numerical valueCalculation | 4 | |
| Empirical Formula from Combustion Datapercentages from combustion analysis | 8 | 8 | Numerical valueCalculation | 5 | |
| Theoretical and Percent Yieldpercentage yield of product | 7 | 7 | Numerical valueCalculation | 7 | |
| Gravimetric Precipitation Analysispercentage halogen by carius method | 6 | 6 | Numerical valueCalculation | 6 | |
| Mole-to-Mole Relationshipsmoles of reactant from product mass | 5 | 5 | Numerical valueCalculation | 3 | |
| Hydrocarbon Combustion General Equationproduct mass from combustion of hydrocarbon | 4 | 4 | Numerical valueCalculation | 2 | |
| POAC in Combustion Analysissample mass from combustion analysis | 3 | 3 | Numerical valueCalculation | 2 | |
| Mass-Volume Stoichiometry at STPmass of reactant from gas volume | 3 | 3 | Numerical valueCalculation | 2 | |
| Mass-Mass Stoichiometrymass of reactant from product mass | 3 | 3 | Numerical valueCalculation | 2 | |
| Stoichiometry of Thermal Decompositionresidue mass on heating salt | 2 | 2 | Numerical valueCalculation | 1 | |
| Eudiometry and Gas Mixture Analysishydrocarbon formula from combustion volumes | 2 | 2 | Numerical valueCalculation | 2 | |
| Mass-Mass Calculationsmass of product from reactant mass | 1 | 1 | Single correctCalculation | – | |
| POAC in Gravimetric Precipitationmass of precipitate from organic product | 1 | 1 | Numerical valueMulti-step | 1 | |
| Percentage Purity Calculationsproduct mass from impure reactant | 1 | 1 | Numerical valueCalculation | 1 | |
| Combustion of Oxygenated Organicsoxygen needed for combustion | 1 | 1 | Single correctCalculation | – | |
| Thermal Decomposition of Carbonatescomposition of mixture from mass loss | 1 | 1 | Single correctCalculation | – | |
| Gaseous Stoichiometrygas volume stoichiometry n2 and h2 | 1 | 1 | Numerical valueCalculation | 1 | |
| Stoichiometry of Sequential Reactionsoverall yield of two-step reaction | 1 | 1 | Numerical valueCalculation | 1 | |
| Thermal Decomposition of Nitratescount bridging atoms in product of reaction sequence | 1 | 1 | Single correctMulti-step | – | |
| Composition of Solid Mixturespercentage of carbonate from two-stage titration | 1 | 1 | Numerical valueMulti-step | 1 | |
| Overall Yield of Sequential Reactionsoverall yield of sequential reactions | 1 | 1 | Numerical valueCalculation | 1 | |
| Reverse Yield Calculationreactant mass from product and yield | 1 | 1 | Numerical valueCalculation | 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
Stoichiometry questions, year by year
The newest 40 show their opening words as they appeared in the official paper; older ones name the idea they tested. Open one for its options and the official answer.
JEE Main 20268 questions in 5 shifts
- 2 Apr, Shift 1Q51The mass of iron converted into by the action of g of steam is : (Given : Molar mass of H, O and Fe are …
Idea: Mass-Mass Calculations
New ideaEasySingle correct - 2 Apr, Shift 2Q51The ratio of mass percentage (w/w) of C : H in a hydrocarbon is 12 : 1. It has two carbon atoms. The weight (in g) of formed…
Idea: Hydrocarbon Combustion General Equation
MediumSingle correct - 2 Apr, Shift 2Q62Complete combustion of X g of an organic compound gave 0.25 g of and 0.12 g of . If the % of carbon is 25% and of hydrogen is…
Idea: POAC in Combustion Analysis
Asked the year beforeMediumSingle correct - 2 Apr, Shift 2Q75Consider the following reactions sequence…
Idea: POAC in Gravimetric Precipitation
New ideaMediumNumerical value - 4 Apr, Shift 2Q75In sulphur estimation, mol of an organic compound (X) (molar mass 76 ) gave 0.4813 g of barium…
Idea: Gravimetric Precipitation Analysis
Asked the year beforeEasyNumerical value - 5 Apr, Shift 1Q51How many grams of residue is obtained by heating 2.76 g of silver carbonate? (Given : Molar mass of C, O and Ag are 12, 16 and 108 g…
Idea: Stoichiometry of Thermal Decomposition
EasySingle correct - 5 Apr, Shift 1Q72In an estimation of sulphur by Carius method 0.2 g of the substance gave 0.6 g of . The percentage of sulphur in the…
Idea: Gravimetric Precipitation Analysis
Asked the year beforeEasyNumerical value - 5 Apr, Shift 2Q51What volume of hydrogen gas at STP would be liberated by action of 50 mL of of 50% purity (density = 1.3 g mL)…
Idea: Limiting Reagent Identification
Asked the year beforeMediumSingle correct
JEE Main 202513 questions in 8 shifts
- 2 Apr, Shift 1Q51Consider the above reaction, what mass of will be…
Idea: Limiting Reagent Identification
MediumSingle correct - 2 Apr, Shift 1Q63On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of and 0.567 g of . The empirical…
Idea: Empirical Formula from Combustion Data
MediumSingle correct - 2 Apr, Shift 2Q64In Dumas' method for estimation of nitrogen, 0.5 gram of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715…
Idea: Stoichiometry of Dumas Method
MediumSingle correct - 3 Apr, Shift 1Q740.5 g of an organic compound on combustion gave 1.46 g of and 0.9 g of . The percentage of carbon in the…
Idea: Empirical Formula from Combustion Data
EasyNumerical value - 3 Apr, Shift 1Q75During estimation of nitrogen by Dumas' method of compound X (0.42 g) [structure X: piperazine, six-membered ring with two NH groups at…
Idea: Stoichiometry of Dumas Method
EasyNumerical value · figure - 3 Apr, Shift 2Q51Mass of magnesium required to produce 220 mL of hydrogen gas at STP on reaction with excess of dil. HCl is Given: Molar mass of Mg is…
Idea: Mass-Volume Stoichiometry at STP
EasySingle correct - 3 Apr, Shift 2Q64In Dumas' method for estimation of nitrogen 0.4 g of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715 mm…
Idea: Stoichiometry of Dumas Method
MediumSingle correct - 4 Apr, Shift 2Q74The amount of calcium oxide produced on heating 150 kg limestone (75% pure) is __________ kg. (Nearest integer) Given : Molar mass (in…
Idea: Percentage Purity Calculations
New ideaEasyNumerical value - 7 Apr, Shift 1Q74An organic compound weighing 500 mg, produced 220 mg of , on complete combustion. The percentage composition of carbon in…
Idea: POAC in Combustion Analysis
EasyNumerical value - 7 Apr, Shift 2Q71Butane reacts with oxygen to produce carbon dioxide and water following the equation given below.…
Idea: Limiting Reagent Identification
EasyNumerical value - 7 Apr, Shift 2Q74In Dumas' method 292 mg of an organic compound released 50 mL of nitrogen gas () at 300 K temperature and 715 mm Hg…
Idea: Stoichiometry of Dumas Method
MediumNumerical value - 8 Apr, Shift 2Q62On combustion 0.210 g of an organic compound containing C, H and O gave 0.127 g and 0.307 g . The…
Idea: Empirical Formula from Combustion Data
MediumSingle correct - 8 Apr, Shift 2Q7120 mL of sodium iodide solution gave 4.74 g silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium…
Idea: Gravimetric Precipitation Analysis
EasyNumerical value
JEE Main 20248 questions in 7 shifts
- 5 Apr, Shift 2Q61The number of moles of methane required to produce 11 g after complete combustion is : (Given molar mass of methane in…
Idea: Mole-to-Mole Relationships
Asked the year beforeEasySingle correct - 8 Apr, Shift 1Q61Combustion of glucose () produces and water. The amount of oxygen (in g) required for the complete…
Idea: Combustion of Oxygenated Organics
New ideaEasySingle correct - 1 Feb, Shift 1Q71In Kjeldahl's method for estimation of nitrogen, acts as :
Idea: Stoichiometry of Kjeldahl Method
EasySingle correct - 1 Feb, Shift 2Q8110 mL of gaseous hydrocarbon on combustion gives 40 mL of and 50 mL of water vapour. Total number of carbon and…
Idea: Eudiometry and Gas Mixture Analysis
EasyNumerical value - 1 Feb, Shift 2Q87Following Kjeldahl's method, 1g of organic compound released ammonia, that neutralised 10 mL of 2M . The percentage of…
Idea: Stoichiometry of Kjeldahl Method
EasyNumerical value - 27 Jan, Shift 1Q81Mass of methane required to produce 22 g of after complete combustion is __________ g. (Given Molar mass in…
Idea: Mass-Mass Stoichiometry
EasyNumerical value - 31 Jan, Shift 1Q81Number of moles of methane required to produce 22g after combustion is moles. The value of…
Idea: Mole-to-Mole Relationships
Asked the year beforeEasyNumerical value - 31 Jan, Shift 2Q61A sample of and weighed 2.21 g is ignited to constant weight of 1.152 g. The composition of mixture is…
Idea: Thermal Decomposition of Carbonates
New ideaMediumSingle correct
JEE Main 20236 questions in 4 shifts
- 8 Apr, Shift 1Q900.5 g of an organic compound (X) with 60% carbon will produce ______ g of on complete combustion.
Idea: Empirical Formula from Combustion Data
Asked the year beforeEasyNumerical value - 11 Apr, Shift 2Q81The volume of hydrogen liberated at STP by treating 2.4 g of magnesium with excess of hydrochloric acid is __________ L…
Idea: Mass-Volume Stoichiometry at STP
Asked the year beforeEasyNumerical value - 13 Apr, Shift 1Q88An organic compound gives 0.220 g of and 0.126 g of on complete combustion. If the % of carbon is 24 then…
Idea: Empirical Formula from Combustion Data
Asked the year beforeEasyNumerical value - 13 Apr, Shift 1Q9020 mL of calcium hydroxide was consumed when it was reacted with 10 mL of unknown solution of . Also 20 mL standard…
Idea: Mole-to-Mole Relationships
Asked the year beforeMediumNumerical value - 13 Apr, Shift 2Q811g of a carbonate () on treatment with excess HCl produces 0.01 mol of . The molar mass of…
Idea: Mole-to-Mole Relationships
Asked the year beforeEasyNumerical value - 13 Apr, Shift 2Q900.400 g of an organic compound (X) gave 0.376 g of AgBr in Carius method for estimation of bromine. % of bromine in the compound (X) is…
Idea: Gravimetric Precipitation Analysis
Asked the year beforeEasyNumerical value
JEE Main 202221 questions in 16 shifts
- 25 Jul, Shift 1Q61on reaction with excess of water results into acidic mixture …
Idea: Mole-to-Mole Relationships
New ideaEasySingle correct - 25 Jul, Shift 1Q88While estimating the nitrogen present in an organic compound by Kjeldahl's method, the ammonia evolved from g of the compound…
Idea: Stoichiometry of Kjeldahl Method
Asked the year beforeEasyNumerical value - 25 Jul, Shift 2Q8156.0 L of nitrogen is mixed with excess of hydrogen gas and it is found that 20 L of ammonia gas is produced. The volume of unused…
Idea: Gaseous Stoichiometry
New ideaMediumNumerical value - 27 Jul, Shift 1Q90In the following reaction [figure: benzene (I) benzene bearing …
Idea: Stoichiometry of Sequential Reactions
New ideaEasyNumerical value · figure - 27 Jul, Shift 2Q90In the above reaction, 5 g of toluene is converted into benzaldehyde with 92% yield. The amount of benzaldehyde produced is __________…
Idea: Theoretical and Percent Yield
Asked the year beforeEasyNumerical value · figure - 28 Jul, Shift 1 · Q90Empirical Formula from Combustion DataAsked the year beforeEasy
- 28 Jul, Shift 2 · Q56Stoichiometry of Dumas MethodAsked the year beforeMedium
- 29 Jul, Shift 1 · Q62Limiting Reagent IdentificationAsked the year beforeEasy
- 29 Jul, Shift 1 · Q89Theoretical and Percent YieldAsked the year beforeMedium
- 29 Jul, Shift 2 · Q61Mass-Mass StoichiometryEasy
- 29 Jul, Shift 2 · Q88Mass-Volume Stoichiometry at STPNew ideaMedium
- 24 Jun, Shift 1 · Q61Hydrocarbon Combustion General EquationAsked the year beforeMedium
- 24 Jun, Shift 1 · Q88Stoichiometry of Kjeldahl MethodAsked the year beforeMedium
- 24 Jun, Shift 2 · Q88Stoichiometry of Dumas MethodAsked the year beforeEasy
- 25 Jun, Shift 2 · Q70Thermal Decomposition of NitratesNew ideaMedium
- 26 Jun, Shift 1 · Q88Empirical Formula from Combustion DataAsked the year beforeEasy
- 28 Jun, Shift 1 · Q90Gravimetric Precipitation AnalysisAsked the year beforeEasy
- 28 Jun, Shift 2 · Q88POAC in Combustion AnalysisNew ideaMedium
- 29 Jun, Shift 1 · Q61Limiting Reagent IdentificationAsked the year beforeEasy
- 29 Jun, Shift 1 · Q88Stoichiometry of Kjeldahl MethodAsked the year beforeEasy
- 30 Jun, Shift 1 · Q81Limiting Reagent IdentificationAsked the year beforeMedium
JEE Main 202120 questions in 15 shifts
- 4 Aug, Shift 2 · Q51Stoichiometry of Thermal DecompositionNew ideaEasy
- 4 Aug, Shift 2 · Q60Overall Yield of Sequential ReactionsNew ideaEasy
- 26 Aug, Shift 2 · Q59Gravimetric Precipitation AnalysisNew ideaMedium
- 27 Aug, Shift 1 · Q60Stoichiometry of Dumas MethodAsked the year beforeHard
- 27 Aug, Shift 2 · Q51Limiting Reagent IdentificationNew ideaMedium
- 31 Aug, Shift 2 · Q60Stoichiometry of Dumas MethodAsked the year beforeEasy
- 24 Feb, Shift 2 · Q51Eudiometry and Gas Mixture AnalysisNew ideaMedium
- 24 Feb, Shift 2 · Q60Theoretical and Percent YieldNew ideaEasy
- 25 Feb, Shift 1 · Q42Empirical Formula from Combustion DataNew ideaEasy
- 25 Feb, Shift 1 · Q51Composition of Solid MixturesNew ideaHard
- 22 Jul, Shift 2 · Q60Theoretical and Percent YieldNew ideaEasy
- 25 Jul, Shift 1 · Q59Hydrocarbon Combustion General EquationAsked the year beforeEasy
- 25 Jul, Shift 2 · Q59Stoichiometry of Kjeldahl MethodAsked the year beforeMedium
- 16 Mar, Shift 2 · Q51Limiting Reagent IdentificationNew ideaMedium
- 16 Mar, Shift 2 · Q60Stoichiometry of Dumas MethodAsked the year beforeMedium
- 17 Mar, Shift 1 · Q60Theoretical and Percent YieldNew ideaEasy
- 17 Mar, Shift 2 · Q42Stoichiometry of Kjeldahl MethodAsked the year beforeMedium
- 17 Mar, Shift 2 · Q60Theoretical and Percent YieldNew ideaMedium
- 18 Mar, Shift 1 · Q59Reverse Yield CalculationNew ideaMedium
- 18 Mar, Shift 2 · Q59Theoretical and Percent YieldNew ideaEasy
JEE Main 20205 questions in 4 shifts
- 8 Jan, Shift 2 · Q40Stoichiometry of Kjeldahl MethodNew ideaEasy
- 8 Jan, Shift 2 · Q46Mass-Mass StoichiometryNew ideaMedium
- 3 Sep, Shift 1 · Q45Stoichiometry of Kjeldahl MethodNew ideaMedium
- 5 Sep, Shift 1 · Q47Hydrocarbon Combustion General EquationNew ideaEasy
- 6 Sep, Shift 2 · Q32Stoichiometry of Dumas MethodNew ideaMedium
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.