JEE Main · Chemistry · Environmental Chemistry
Environmental Chemistry: JEE Main previous year questions
61 questions in the 108 JEE Main shifts Lumi analysed, in 6 of 8 years. Pattern: Gone quiet. 1 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 61
- in 61 of 108 shifts
- Years asked
- 6/8
- last asked 2024
- Since 2024
- Quiet
- 1 question in 2024–26
- Weighted estimate
- –
- history: 0.4 a shift on average, typically 0.0–0.8
Key findings
- 01
Asked in 6 of 8 years with analysed shifts and in 61 of 108 shifts: 61 questions, #38 of 196 topics. The years that asked it were 1.4 apart on average. Last asked in 2024.
- 02
37% of its questions since 2020 tested an idea no earlier year had asked; 35 repeated an idea from the year before.
- 03
The most repeated idea is Ozone Layer Depletion, asked 8 times in 8 shifts (2020, 2021, 2022, 2023), most often as “identify step not in ozone depletion mechanism”.
- 04
JEE Main has asked 19 of the 56 ideas in this topic; 28 have never been asked, directly or inside another question.
- 05
Mostly asked as single correct (62%); 0% need a numerical answer, 80% are easy and 0% hard. It went down from 0.7 to 0.0 questions a shift since 2024.
- 06
The skill tested most is recall (75%), then conceptual (25%).
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: 1 in 1 shift · 2020: 6 in 12 shifts · 2021: 23 in 24 shifts · 2022: 20 in 24 shifts · 2023: 10 in 12 shifts · 2024: 1 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.
- Up to 2023
- 0.7
- a shift, of 25
- Since 2024
- 0.0
- -0.7
- Usual gap
- 1.4 yrs
- between years asking it
- Shifts with it
- 61/108
- 56% of analysed shifts
How it is asked
Difficulty, format and skill
Across all 61 questions on Environmental Chemistry since 2017.
Difficulty
QUESTIONS- Easy49 · 80%
- Medium12 · 20%
- Hard0 · 0%
Format
SHARE- Single correct · 38 Q62%
- Two statements · 9 Q15%
- Other · 6 Q10%
- Match the list · 5 Q8%
- Assertion–reason · 3 Q5%
Skill tested
SHARE- Recall · 46 Q75%
- Conceptual · 15 Q25%
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 19 of the 56 ideas in this topic. 28 have never been asked yet.
- Asked directly19 · 34%
- Touched inside another question9 · 16%
- 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
19 different ideas were tested; 15 came more than once.
identify step not in ozone depletion mechanism
Single correct · 8 shiftsconditions favouring photochemical smog
Single correct · 7 shiftsidentify acid responsible for damage
Single correct · 6 shiftstrue statement selection on greenhouse gases
Other · 6 shiftsstatement i/ii on water quality parameters
Single correct · 5 shiftsconsequence of eutrophication
Single correct · 5 shiftsidentify formula of compound
Single correct · 3 shiftsassertion-reason on environmental chemistry
Assertion–reason · 3 shiftsmatch list on industry and waste generated
Match the list · 2 shiftsidentify group of chemicals used as pesticides
Single correct · 2 shiftsidentify condition for smog
Single correct · 2 shiftsstatement i/ii on water pollution
Single correct · 2 shiftsidentify agent not used in application
Single correct · 2 shiftsreagent identification in ozone depletion reactions
Single correct · 2 shiftsodd-one-out among components of smog
Assertion–reason · 2 shiftsidentify pollutant by effect
Single correct · 1 shiftstatements on acid rain ph and causes
Two statements · 1 shiftmatch list on pollutants and diseases
Match the list · 1 shiftdefinition recall
Single correct · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Ozone Layer Depletionidentify step not in ozone depletion mechanism | 8 | 8 | Single correctRecall | – | |
| Classical vs Photochemical Smogconditions favouring photochemical smog | 7 | 7 | Single correctConceptual | – | |
| Acid Rain Mechanismidentify acid responsible for damage | 6 | 6 | Single correctRecall | – | |
| Greenhouse Effecttrue statement selection on greenhouse gases | 6 | 6 | OtherRecall | – | |
| Water Quality BOD and CODstatement i/ii on water quality parameters | 5 | 5 | Single correctRecall | – | |
| Eutrophication and Dissolved Oxygen Limitsconsequence of eutrophication | 5 | 5 | Single correctConceptual | – | |
| Drinking Water Standards: Fluoride Limitsidentify formula of compound | 3 | 3 | Single correctRecall | – | |
| Fluoride Limits in Drinking Waterassertion-reason on environmental chemistry | 3 | 3 | Assertion–reasonRecall | – | |
| Non-Biodegradable Industrial Solid Wastesmatch list on industry and waste generated | 2 | 2 | Match the listRecall | – | |
| Pesticides and Herbicides Toxicityidentify group of chemicals used as pesticides | 2 | 2 | Single correctRecall | – | |
| Primary Reactions of Photochemical Smogidentify condition for smog | 2 | 2 | Single correctConceptual | – | |
| BOD Values for Clean vs Polluted Waterstatement i/ii on water pollution | 2 | 2 | Single correctConceptual | – | |
| Green Chemistry Alternatives in Daily Applicationsidentify agent not used in application | 2 | 2 | Single correctRecall | – | |
| Role of Polar Stratospheric Clouds (PSCs)reagent identification in ozone depletion reactions | 2 | 2 | Single correctRecall | – | |
| Secondary Pollutants in Photochemical Smogodd-one-out among components of smog | 2 | 2 | Assertion–reasonRecall | – | |
| NO2 and Traffic Red Hazeidentify pollutant by effect | 1 | 1 | Single correctRecall | – | |
| Acid Rain pH Thresholdstatements on acid rain ph and causes | 1 | 1 | Two statementsRecall | – | |
| Nitrate Limit and Blue Baby Syndromematch list on pollutants and diseases | 1 | 1 | Match the listRecall | – | |
| Stratospheric Ozone Formationdefinition recall | 1 | 1 | Single correctRecall | – |
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
Environmental Chemistry 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 20241 question in 1 shift
- 9 Apr, Shift 1Q67The ions make the enamel on teeth much harder by converting hydroxyapatite (the enamel on the surface of teeth) into much…
Idea: Drinking Water Standards: Fluoride Limits
MediumSingle correct
JEE Main 202310 questions in 10 shifts
- 6 Apr, Shift 1Q71The possibility of photochemical smog formation is more at
Idea: Classical vs Photochemical Smog
Asked the year beforeEasySingle correct - 6 Apr, Shift 2Q71The group of chemicals used as pesticide is
Idea: Pesticides and Herbicides Toxicity
Asked the year beforeEasySingle correct - 8 Apr, Shift 2Q70Which of these reactions is not a part of breakdown of ozone in stratosphere?
Idea: Ozone Layer Depletion
Asked the year beforeMediumSingle correct - 10 Apr, Shift 1Q70Match List I with List II List I (Industry) List II (Waste Generated) (A) Steel plants (I) Gypsum (B) Thermal power plants (II) Fly ash…
Idea: Non-Biodegradable Industrial Solid Wastes
Asked the year beforeEasyMatch the list - 11 Apr, Shift 1Q71Given below are two statements: Statement I: If BOD is 4 ppm and dissolved oxygen is 8 ppm, then it is a good quality water. Statement II:…
Idea: Water Quality BOD and COD
Asked the year beforeMediumTwo statements - 11 Apr, Shift 2Q71Which of the following compounds is an example of Freon?
Idea: Ozone Layer Depletion
Asked the year beforeEasySingle correct - 12 Apr, Shift 1Q73Match List I with List II LIST I / LIST II A. Nitrogen oxides in air - I. Eutrophication B. Methane in air - II. pH of rain water becomes…
Idea: Acid Rain Mechanism
Asked the year beforeEasyMatch the list - 13 Apr, Shift 1Q72The radical which mainly causes ozone depletion in the presence of UV radiations is :
Idea: Ozone Layer Depletion
Asked the year beforeEasySingle correct - 13 Apr, Shift 2Q71Which of the following are the Green house gases? A. Water vapour B. Ozone C. D. Molecular hydrogen Choose the most…
Idea: Greenhouse Effect
Asked the year beforeEasyOther - 15 Apr, Shift 1Q71The possibility of photochemical smog formation will be minimum at
Idea: Primary Reactions of Photochemical Smog
EasySingle correct
JEE Main 202220 questions in 20 shifts
- 25 Jul, Shift 1Q72The photochemical smog does not generally contain :
Idea: Classical vs Photochemical Smog
Asked the year beforeEasySingle correct - 25 Jul, Shift 2Q72Match List I with List II. List I | List II A. Sulphate | I. Pesticide B. Fluoride | II. Bending of bones C. Nicotine | III. Laxative…
Idea: Drinking Water Standards: Fluoride Limits
Asked the year beforeMediumMatch the list - 26 Jul, Shift 1Q70A and B in the above atmospheric reaction step are :
Idea: Ozone Layer Depletion
Asked the year beforeEasySingle correct - 27 Jul, Shift 1Q73Match List I with List II. List I (Pollutant) | List II (Disease/sickness) A. Sulphate (>500 ppm) | I. Methemoglobinemia B. Nitrate (>50…
Idea: Fluoride Limits in Drinking Water
Asked the year beforeMediumMatch the list - 27 Jul, Shift 2Q71Given below are two statements : **Statement I :** The non bio-degradable fly ash and slag from steel industry can be used by cement…
Idea: Non-Biodegradable Industrial Solid Wastes
New ideaEasyTwo statements - 28 Jul, Shift 1Q71Given below are two statements : Statement I : In polluted water values of both dissolved oxygen and BOD are very low. Statement II :…
Idea: BOD Values for Clean vs Polluted Water
Asked the year beforeEasyTwo statements - 29 Jul, Shift 2Q72Dinitrogen is a robust compound, but reacts at high altitudes to form oxides. The oxide of nitrogen that can damage plant leaves and…
Idea: NO2 and Traffic Red Haze
New ideaEasySingle correct - 30 Jul, Shift 2Q41Which of the following is not a component of photochemical smog?
Idea: Secondary Pollutants in Photochemical Smog
Asked the year beforeEasySingle correct - 24 Jun, Shift 2Q72Some gases are responsible for heating of atmosphere (green house effect). Identify from the following the gaseous species which does not…
Idea: Greenhouse Effect
Asked the year beforeEasySingle correct - 25 Jun, Shift 1Q70The eutrophication of water body results in :
Idea: Eutrophication and Dissolved Oxygen Limits
Asked the year beforeEasySingle correct - 25 Jun, Shift 2Q72Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Polluted water may have…
Idea: Water Quality BOD and COD
Asked the year beforeMediumAssertion–reason - 26 Jun, Shift 1Q72Polar stratospheric clouds facilitate the formation of :
Idea: Role of Polar Stratospheric Clouds (PSCs)
New ideaEasySingle correct - 26 Jun, Shift 2Q70The measured BOD values for four different water samples (A-D) are as follows: A = 3 ppm; B=18 ppm; C=21 ppm; D=4 ppm. The water samples…
Idea: Water Quality BOD and COD
Asked the year beforeEasySingle correct - 27 Jun, Shift 1Q72Given below are two Statements : Statement I : Classical smog occurs in cool humid climate. It is a reducing mixture of smoke, fog and…
Idea: Classical vs Photochemical Smog
Asked the year beforeEasyTwo statements - 27 Jun, Shift 2Q71On the surface of polar stratospheric clouds, hydrolysis of chlorine nitrate gives A and B while its reaction with HCl produces B and C.…
Idea: Role of Polar Stratospheric Clouds (PSCs)
New ideaMediumSingle correct - 28 Jun, Shift 1Q70Which amongst the following is not a pesticide ?
Idea: Pesticides and Herbicides Toxicity
New ideaEasySingle correct - 28 Jun, Shift 2Q72Correct statement about photo-chemical smog is :
Idea: Classical vs Photochemical Smog
Asked the year beforeEasySingle correct - 29 Jun, Shift 1Q72The acid that is believed to be mainly responsible for the damage of Taj Mahal is
Idea: Acid Rain Mechanism
Asked the year beforeEasySingle correct - 29 Jun, Shift 2Q72Sulphur dioxide is one of the components of polluted air. is also a major contributor to acid rain. The correct and…
Idea: Acid Rain Mechanism
Asked the year beforeEasySingle correct - 30 Jun, Shift 1Q72Which one of the following chemicals has not been used for the dry cleaning of clothes ?
Idea: Green Chemistry Alternatives in Daily Applications
Asked the year beforeEasySingle correct
JEE Main 202123 questions in 23 shifts
- 3 Aug, Shift 1Q40Match List I with List II : List I : A. ‘Blue baby’ syndrome ; B. Eutrophication ; C. Minimata disease ; D. Itai-Itai disease List II : I.…
Idea: Nitrate Limit and Blue Baby Syndrome
New ideaEasyMatch the list - 3 Aug, Shift 2Q41Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A : Fluoride ion…
Idea: Fluoride Limits in Drinking Water
EasyAssertion–reason - 4 Aug, Shift 1Q41In stratosphere, chlorofluorocarbon compounds break down by UV radiations, releasing 'X' free radical, which further causes ozone layer…
Idea: Ozone Layer Depletion
Asked the year beforeEasySingle correct - 4 Aug, Shift 2Q40The INCORRECT statement among those given below regarding smog is
Idea: Classical vs Photochemical Smog
New ideaEasySingle correct - 26 Aug, Shift 1Q40The conversion of hydroxyapatite occurs due to presence of ions in water. The correct formula of hydroxyapatite is :
Idea: Drinking Water Standards: Fluoride Limits
New ideaMediumSingle correct - 26 Aug, Shift 2Q41Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Photochemical…
Idea: Secondary Pollutants in Photochemical Smog
New ideaEasyAssertion–reason - 27 Aug, Shift 1Q41The gas ‘A’ is having very low reactivity reaches to stratosphere. It is non-toxic and non-flammable but dissociated by UV-radiations in…
Idea: Ozone Layer Depletion
Asked the year beforeEasySingle correct · figure - 27 Aug, Shift 2Q39In stratosphere most of the ozone formation is assisted by :
Idea: Stratospheric Ozone Formation
New ideaEasySingle correct - 31 Aug, Shift 1Q41BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively as :
Idea: BOD Values for Clean vs Polluted Water
New ideaEasySingle correct - 31 Aug, Shift 2 · Q40Acid Rain MechanismAsked the year beforeEasy
- 24 Feb, Shift 1 · Q39Greenhouse EffectAsked the year beforeEasy
- 24 Feb, Shift 2 · Q41Water Quality BOD and CODAsked the year beforeEasy
- 25 Feb, Shift 1 · Q41Classical vs Photochemical SmogNew ideaMedium
- 25 Feb, Shift 2 · Q40Acid Rain pH ThresholdNew ideaEasy
- 26 Feb, Shift 1 · Q39Primary Reactions of Photochemical SmogNew ideaEasy
- 22 Jul, Shift 2 · Q41Eutrophication and Dissolved Oxygen LimitsAsked the year beforeEasy
- 25 Jul, Shift 1 · Q40Green Chemistry Alternatives in Daily ApplicationsNew ideaMedium
- 25 Jul, Shift 2 · Q41Ozone Layer DepletionAsked the year beforeMedium
- 16 Mar, Shift 2 · Q40Greenhouse EffectAsked the year beforeEasy
- 17 Mar, Shift 1 · Q40Classical vs Photochemical SmogNew ideaEasy
- 17 Mar, Shift 2 · Q41Eutrophication and Dissolved Oxygen LimitsAsked the year beforeEasy
- 18 Mar, Shift 1 · Q41Greenhouse EffectAsked the year beforeMedium
- 18 Mar, Shift 2 · Q41Eutrophication and Dissolved Oxygen LimitsAsked the year beforeEasy
JEE Main 20206 questions in 6 shifts
- 8 Jan, Shift 1 · Q38Greenhouse EffectNew ideaEasy
- 9 Jan, Shift 2 · Q38Water Quality BOD and CODNew ideaEasy
- 2 Sep, Shift 1 · Q38Ozone Layer DepletionNew ideaEasy
- 3 Sep, Shift 1 · Q38Acid Rain MechanismNew ideaEasy
- 3 Sep, Shift 2 · Q38Acid Rain MechanismNew ideaEasy
- 5 Sep, Shift 1 · Q39Eutrophication and Dissolved Oxygen LimitsNew ideaEasy
JEE Main 20171 question in 1 shift
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.
More topics in Environmental Chemistry
This is the only topic tagged in this chapter.