JEE Main · Chemistry · Surface Chemistry
Colloids: JEE Main previous year questions
39 questions in the 108 JEE Main shifts Lumi analysed, in 5 of 8 years. Pattern: Gone quiet. 0 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 39
- in 38 of 108 shifts
- Years asked
- 5/8
- last asked 2023
- Since 2024
- Quiet
- 0 questions in 2024–26
- Weighted estimate
- –
- history: 0.3 a shift on average, typically 0.0–0.6
Key findings
- 01
Asked in 5 of 8 years with analysed shifts and in 38 of 108 shifts: 39 questions, #85 of 196 topics. The years that asked it were 1.5 apart on average. Last asked in 2023.
- 02
45% of its questions since 2020 tested an idea no earlier year had asked; 19 repeated an idea from the year before.
- 03
The most repeated idea is Colloid Classification by State, asked 6 times in 6 shifts (2020, 2021, 2022, 2023), most often as “count colloids with a given dispersion medium”.
- 04
JEE Main has asked 16 of the 40 ideas in this topic; 19 have never been asked, directly or inside another question.
- 05
Mostly asked as single correct (62%); 8% need a numerical answer, 62% are easy and 0% hard. It went down from 0.5 to 0.0 questions a shift since 2024.
- 06
The skill tested most is conceptual (51%), then recall (28%).
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: 7 in 12 shifts · 2021: 13 in 24 shifts · 2022: 12 in 24 shifts · 2023: 6 in 12 shifts · 2024: 0 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.
- Up to 2023
- 0.5
- a shift, of 25
- Since 2024
- 0.0
- -0.5
- Usual gap
- 1.5 yrs
- between years asking it
- Shifts with it
- 38/108
- 35% of analysed shifts
How it is asked
Difficulty, format and skill
Across all 39 questions on Colloids since 2017.
Difficulty
QUESTIONS- Easy24 · 62%
- Medium15 · 38%
- Hard0 · 0%
Format
SHARE- Single correct · 24 Q62%
- Match the list · 5 Q13%
- Assertion–reason · 3 Q8%
- Numerical value · 3 Q8%
- Other · 2 Q5%
- Two statements · 1 Q3%
- Diagram based · 1 Q3%
Skill tested
SHARE- Conceptual · 20 Q51%
- Recall · 11 Q28%
- Application · 4 Q10%
- Calculation · 3 Q8%
- Diagram reading · 1 Q3%
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 16 of the 40 ideas in this topic. 19 have never been asked yet.
- Asked directly16 · 40%
- Touched inside another question5 · 13%
- Never asked19 · 48%
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.
16 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
16 different ideas were tested; 7 came more than once.
count colloids with a given dispersion medium
Match the list · 6 shifts · 1 numericalorder/ranking of flocculation values
Single correct · 5 shifts · 1 numericaltrue statement selection on colloids
Single correct · 5 shiftsassertion-reason on tyndall effect
Single correct · 5 shiftstrue statement selection on micelle structure
Single correct · 5 shiftsrelative coagulating power from values
Numerical value · 2 shifts · 1 numericalproperty related to zeta potential
Single correct · 2 shiftsassertion-reason on colloid colour
Assertion–reason · 1 shiftmatch list on colloids
Match the list · 1 shiftassertion-reason on colloid dialysis
Assertion–reason · 1 shiftstatement i/ii on emulsions
Two statements · 1 shiftcharge on colloid from fecl3 in hot water
Single correct · 1 shifttrue statement selection on colloidal solutions
Single correct · 1 shiftidentify sol formed on mixing reagents
Single correct · 1 shiftidentify method for preparing colloids
Single correct · 1 shiftidentify protective colloid in a sol
Single correct · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Colloid Classification by Statecount colloids with a given dispersion medium | 6 | 6 | Match the listRecall | 1 | |
| Hardy-Schulze Ruleorder/ranking of flocculation values | 5 | 5 | Single correctApplication | 1 | |
| Lyophilic and Lyophobic Solstrue statement selection on colloids | 5 | 5 | Single correctConceptual | – | |
| Optical and Kinetic Propertiesassertion-reason on tyndall effect | 5 | 5 | Single correctConceptual | – | |
| Micelle Formation and CMCtrue statement selection on micelle structure | 5 | 5 | Single correctConceptual | – | |
| Flocculation Value Calculationrelative coagulating power from values | 2 | 2 | Numerical valueCalculation | 1 | |
| Zeta Potential and Helmholtz Double Layerproperty related to zeta potential | 2 | 2 | Single correctApplication | – | |
| Colour Dependence on Particle Sizeassertion-reason on colloid colour | 1 | 1 | Assertion–reasonConceptual | – | |
| Macromolecular Colloidsmatch list on colloids | 1 | 1 | Match the listRecall | – | |
| Peptization and Dialysisassertion-reason on colloid dialysis | 1 | 1 | Assertion–reasonConceptual | – | |
| Role of Emulsifying Agentsstatement i/ii on emulsions | 1 | 1 | Two statementsConceptual | – | |
| Chemical Methods of Preparationcharge on colloid from fecl3 in hot water | 1 | 1 | Single correctConceptual | – | |
| Colligative Properties of Colloidstrue statement selection on colloidal solutions | 1 | 1 | Single correctConceptual | – | |
| Predicting Sol Charge via Excess Reagentidentify sol formed on mixing reagents | 1 | 1 | Single correctApplication | – | |
| Bredig's Arc Methodidentify method for preparing colloids | 1 | 1 | Single correctRecall | – | |
| Protective Colloids and Gold Numberidentify protective colloid in a sol | 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
Colloids 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 20236 questions in 6 shifts
- 6 Apr, Shift 2Q87The number of colloidal systems from the following, which will have 'liquid' as the dispersion medium, is ______________. Gem stones,…
Idea: Colloid Classification by State
Asked the year beforeMediumNumerical value - 8 Apr, Shift 2Q87Coagulating value of the electrolytes and NaCl for are 0.09 and 50.04 respectively. The coagulating…
Idea: Flocculation Value Calculation
Asked the year beforeEasyNumerical value - 10 Apr, Shift 2Q63Ferric chloride is applied to stop bleeding because -
Idea: Hardy-Schulze Rule
EasySingle correct - 13 Apr, Shift 1Q63What happens when a lyophilic sol is added to a lyophobic sol?
Idea: Lyophilic and Lyophobic Sols
Asked the year beforeEasySingle correct - 13 Apr, Shift 2Q63Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : The diameter of…
Idea: Optical and Kinetic Properties
Asked the year beforeMediumAssertion–reason - 15 Apr, Shift 1Q8620 mL of 0.5 M NaCl is required to coagulate 200 mL of solution in 2 hours. The coagulating value of NaCl is __________.
Idea: Hardy-Schulze Rule
EasyNumerical value
JEE Main 202212 questions in 11 shifts
- 25 Jul, Shift 2Q65For micelle formation, which of the following statements are correct ? A. Micelle formation is an exothermic process. B. Micelle formation…
Idea: Micelle Formation and CMC
Asked the year beforeMediumOther - 26 Jul, Shift 2Q65Given below are two statements: one is labelled as **Assertion A** and the other is labelled as **Reason R**. **Assertion A:** Finest gold…
Idea: Colour Dependence on Particle Size
New ideaMediumAssertion–reason - 27 Jul, Shift 2Q65Given below are two statements : one is labelled as **Assertion (A)** and the other is labelled as **Reason (R)**. **Assertion (A) :**…
Idea: Peptization and Dialysis
New ideaMediumAssertion–reason - 29 Jul, Shift 1Q63100 mL of 5% (w/v) solution of NaCl in water was prepared in 250 mL beaker. Albumin from the egg was poured into NaCl solution and stirred…
Idea: Lyophilic and Lyophobic Sols
Asked the year beforeMediumSingle correct - 24 Jun, Shift 1Q65Given below are two statements : Statement I : Emulsions of oil in water are unstable and sometimes they separate into two layers on…
Idea: Role of Emulsifying Agents
New ideaMediumTwo statements - 25 Jun, Shift 1Q62**Incorrect** statement for Tyndall effect is :
Idea: Optical and Kinetic Properties
Asked the year beforeEasySingle correct - 25 Jun, Shift 1Q79Using very little soap while washing clothes, does not serve the purpose of cleaning of clothes, because :
Idea: Micelle Formation and CMC
Asked the year beforeEasySingle correct - 27 Jun, Shift 1Q64Match List - I with List - II. List - I (A) Lyophilic colloid (B) Emulsion (C) Positively charged colloid (D) Negatively charged colloid…
Idea: Colloid Classification by State
Asked the year beforeEasyMatch the list - 28 Jun, Shift 1Q62The Zeta potential is related to which property of colloids ?
Idea: Zeta Potential and Helmholtz Double Layer
Asked the year beforeEasySingle correct - 28 Jun, Shift 2Q65Match List - I with List - II : List - I | List - II (A) negatively charged sol | (I) (B) macromolecular…
Idea: Macromolecular Colloids
New ideaEasyMatch the list - 29 Jun, Shift 1Q65Which of the following is a correct statement ?
Idea: Lyophilic and Lyophobic Sols
Asked the year beforeEasySingle correct - 29 Jun, Shift 2Q65A 42.12% (w/v) solution of NaCl causes precipitation of a certain sol in 10 hours. The coagulating value of NaCl for the sol is [Given:…
Idea: Flocculation Value Calculation
New ideaMediumSingle correct
JEE Main 202113 questions in 13 shifts
- 4 Aug, Shift 2Q31Match List-I with List-II : List-I : Examples of Colloids A. Paints B. Hair cream C. Whipped cream D. Cheese List-II : Type of Colloid I.…
Idea: Colloid Classification by State
Asked the year beforeEasyMatch the list · figure - 26 Aug, Shift 2Q33The sol given below with negatively charged colloidal particles is :
Idea: Zeta Potential and Helmholtz Double Layer
New ideaMediumSingle correct - 27 Aug, Shift 1Q34Tyndall effect is more effectively shown by :
Idea: Optical and Kinetic Properties
Asked the year beforeEasySingle correct - 27 Aug, Shift 2Q31Lyophilic sols are more stable than lyophobic sols because,
Idea: Lyophilic and Lyophobic Sols
New ideaEasySingle correct - 24 Feb, Shift 2Q33Most suitable salt which can be used for efficient clotting of blood will be :
Idea: Hardy-Schulze Rule
Asked the year beforeEasySingle correct - 25 Feb, Shift 2Q33Which one of the following statements is FALSE for hydrophilic sols ?
Idea: Lyophilic and Lyophobic Sols
New ideaEasySingle correct - 26 Feb, Shift 2Q32The nature of charge on resulting colloidal particles when is added to excess of hot water is :
Idea: Chemical Methods of Preparation
New ideaMediumSingle correct - 22 Jul, Shift 2Q33When silver nitrate solution is added to potassium iodide solution then the sol produced is :
Idea: Predicting Sol Charge via Excess Reagent
New ideaMediumSingle correct - 25 Jul, Shift 1Q32Sodium stearate is an anionic surfactant which forms micelles in oil. Choose the correct statement for…
Idea: Micelle Formation and CMC
Asked the year beforeMediumSingle correct - 25 Jul, Shift 2Q33Match List I with List II : List - I Example of Colloids (a) Cheese (b) Pumice stone (c) Hair cream (d) Cloud List - II Classification (i)…
Idea: Colloid Classification by State
Asked the year beforeEasyMatch the list - 16 Mar, Shift 2Q32The INCORRECT statements below regarding colloidal solutions is :
Idea: Colligative Properties of Colloids
New ideaEasySingle correct - 17 Mar, Shift 1Q32A colloidal system consisting of a gas dispersed in a solid is called a/an :
Idea: Colloid Classification by State
Asked the year beforeEasySingle correct - 17 Mar, Shift 2Q33For the coagulation of a negative sol, the species below, that has the highest flocculating power is :
Idea: Hardy-Schulze Rule
Asked the year beforeEasySingle correct
JEE Main 20207 questions in 7 shifts
- 8 Jan, Shift 1Q28As per Hardy-Schulze formulation, the flocculation values of the following for ferric hydroxide sol are in the order :
Idea: Hardy-Schulze Rule
New ideaMediumSingle correct - 2 Sep, Shift 1Q28Which of the following is used for the preparation of colloids ?
Idea: Bredig's Arc Method
New ideaEasySingle correct - 3 Sep, Shift 1Q31Tyndall effect is observed when :
Idea: Optical and Kinetic Properties
Asked the year beforeEasySingle correct - 3 Sep, Shift 2Q26An ionic micelle is formed on the addition of :
Idea: Micelle Formation and CMC
New ideaMediumSingle correct · figure - 4 Sep, Shift 1Q26Match the following : (i) Foam (a) smoke (ii) Gel (b) cell fluid (iii) Aerosol (c) jellies (iv) Emulsion (d) rubber (e) froth (f) milk
Idea: Colloid Classification by State
New ideaEasyMatch the list - 4 Sep, Shift 2Q26A sample of red ink (a colloidal suspension) is prepared by mixing eosin dye, egg white, HCHO and water. The component which ensures…
Idea: Protective Colloids and Gold Number
New ideaEasySingle correct - 5 Sep, Shift 1Q45Identify the correct molecular picture showing what happens at the critical micellar concentration (CMC) of an aqueous solution of a…
Idea: Micelle Formation and CMC
New ideaEasyDiagram based · figure
JEE Main 20171 question in 1 shift
- 2 Apr (offline)Q34The Tyndall effect is observed only when following conditions are satisfied : (a) The diameter of the dispersed particles is much smaller…
Idea: Optical and Kinetic Properties
MediumOther
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.