JEE Main · Chemistry · Equilibrium
pH and Buffers: JEE Main previous year questions
45 questions in the 108 JEE Main shifts Lumi analysed, in 8 of 8 years. Pattern: Asked most years. 14 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 45
- in 40 of 108 shifts
- Years asked
- 8/8
- last asked 2026
- Weighted estimate
- 0.4
- model; history: 0.4 a shift on average, typically 0.3–0.7
Key findings
- 01
Asked in 8 of 8 years with analysed shifts and in 40 of 108 shifts: 45 questions, #70 of 196 topics. It came in every year with analysed shifts.
- 02
55% of its questions since 2020 tested an idea no earlier year had asked; 8 repeated an idea from the year before.
- 03
The most repeated idea is pH of Strong Acids and Bases, asked 7 times in 7 shifts (2021, 2022, 2023, 2025), most often as “ph after dilution of strong acid”.
- 04
JEE Main has asked 22 of the 51 ideas in this topic; 23 have never been asked, directly or inside another question.
- 05
Mostly asked as numerical value (51%); 51% need a numerical answer, 36% are easy and 11% hard.
- 06
The skill tested most is calculation (64%), then conceptual (20%).
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: 4 in 12 shifts · 2021: 11 in 24 shifts · 2022: 11 in 24 shifts · 2023: 4 in 12 shifts · 2024: 5 in 18 shifts · 2025: 3 in 8 shifts · 2026: 6 in 9 shifts.
- Up to 2023
- 0.4
- a shift, of 25
- Since 2024
- 0.4
- 0.0
- Usual gap
- 1.3 yrs
- between years asking it
- Shifts with it
- 40/108
- 37% of analysed shifts
Revise first
- pH of Strong Acids and Bases · asked 2021, 2022, 2023, 2025
- pH of Weak Acid-Weak Base Salts · asked 2017, 2021, 2024
- pH of Weak Acids and Bases · asked 2020, 2021, 2022, 2026
How it is asked
Difficulty, format and skill
Across all 45 questions on pH and Buffers since 2017.
Difficulty
QUESTIONS- Easy16 · 36%
- Medium24 · 53%
- Hard5 · 11%
Format
SHARE- Numerical value · 23 Q51%
- Single correct · 13 Q29%
- Two statements · 4 Q9%
- Other · 2 Q4%
- Assertion–reason · 2 Q4%
- Diagram based · 1 Q2%
Skill tested
SHARE- Calculation · 29 Q64%
- Conceptual · 9 Q20%
- Multi-step · 3 Q7%
- Recall · 2 Q4%
- Application · 1 Q2%
- Data or graph · 1 Q2%
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 22 of the 51 ideas in this topic. 23 have never been asked yet.
- Asked directly22 · 43%
- Touched inside another question6 · 12%
- Never asked23 · 45%
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.
22 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
22 different ideas were tested; 11 came more than once.
ph after dilution of strong acid
Numerical value · 7 shifts · 6 numericalph at half neutralisation of weak acid
Numerical value · 4 shifts · 2 numericalexpression for degree of dissociation
Numerical value · 4 shifts · 3 numericalph of weak acid weak base salt
Numerical value · 4 shifts · 2 numericalph of basic buffer mixture
Numerical value · 3 shifts · 2 numericalph at stages of weak acid titration
Numerical value · 2 shifts · 1 numericalspecies concentration in polyprotic acid
Numerical value · 2 shifts · 1 numericalorder/ranking of ph of mixtures
Diagram based · 2 shiftsstatement i/ii on acid-base titration
Two statements · 2 shiftsassertion-reason on acid-base indicator
Assertion–reason · 2 shiftsph after partial titration of weak base
Numerical value · 2 shifts · 1 numericalph change of buffer on acid addition
Numerical value · 1 shift · 1 numericalstatement pair on buffer definition and blood buffer
Two statements · 1 shiftbuffer volume from ph
Numerical value · 1 shift · 1 numericalph after partial neutralisation of weak acid
Numerical value · 1 shift · 1 numericalstatements on phenolphthalein indicator from titration curve
Numerical value · 1 shift · 1 numericalcount correct statements on ionic equilibrium
Other · 1 shiftchoice of indicator for titration
Single correct · 1 shiftph of mixture of strong acids
Single correct · 1 shiftph of weak base and strong acid mixture
Single correct · 1 shiftdegree of dissociation of weak acid in strong acid
Numerical value · 1 shift · 1 numericalassertion-reason
Assertion–reason · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| pH of Strong Acids and Basesph after dilution of strong acid | 7 | 7 | Numerical valueCalculation | 6 | |
| Acidic Buffer pH Calculationph at half neutralisation of weak acid | 4 | 4 | Numerical valueCalculation | 2 | |
| pH of Weak Acids and Basesexpression for degree of dissociation | 4 | 4 | Numerical valueMulti-step | 3 | |
| pH of Weak Acid-Weak Base Saltsph of weak acid weak base salt | 4 | 4 | Numerical valueCalculation | 2 | |
| Basic Buffer pH Calculationph of basic buffer mixture | 3 | 3 | Numerical valueCalculation | 2 | |
| pH at Titration Half-Equivalence Pointph at stages of weak acid titration | 2 | 2 | Numerical valueCalculation | 1 | |
| pH of Polyprotic Acidsspecies concentration in polyprotic acid | 2 | 2 | Numerical valueCalculation | 1 | |
| pH of Strong Acid and Strong Base Mixturesorder/ranking of ph of mixtures | 2 | 2 | Diagram basedCalculation | – | |
| Indicator Selection for Titrationsstatement i/ii on acid-base titration | 2 | 2 | Two statementsConceptual | – | |
| Predicting Indicator Colorassertion-reason on acid-base indicator | 2 | 2 | Assertion–reasonConceptual | – | |
| Buffer Formation via Partial Neutralizationph after partial titration of weak base | 2 | 2 | Numerical valueApplication | 1 | |
| pH Change on Adding Strong Acid/Base to Bufferph change of buffer on acid addition | 1 | 1 | Numerical valueCalculation | 1 | |
| Buffer Capacity and Rangestatement pair on buffer definition and blood buffer | 1 | 1 | Two statementsConceptual | – | |
| Volume Ratios for Buffer Preparationbuffer volume from ph | 1 | 1 | Numerical valueCalculation | 1 | |
| Buffer Formation via Partial Neutralizationph after partial neutralisation of weak acid | 1 | 1 | Numerical valueCalculation | 1 | |
| pH of Acid-Base Indicatorsstatements on phenolphthalein indicator from titration curve | 1 | 1 | Numerical valueConceptual | 1 | |
| pH of Extremely Dilute Strong Acids/Basescount correct statements on ionic equilibrium | 1 | 1 | OtherConceptual | – | |
| Acid-Base Indicator Transition Rangechoice of indicator for titration | 1 | 1 | Single correctConceptual | – | |
| pH of Mixed Strong Acidsph of mixture of strong acids | 1 | 1 | Single correctCalculation | – | |
| pH of Salt Solutionsph of weak base and strong acid mixture | 1 | 1 | Single correctMulti-step | – | |
| Common Ion Effect on Weak Acid pHdegree of dissociation of weak acid in strong acid | 1 | 1 | Numerical valueCalculation | 1 | |
| Temperature Dependence of Kw and Neutral pHassertion-reason | 1 | 1 | Assertion–reasonConceptual | – |
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
pH and Buffers 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 20266 questions in 5 shifts
- 2 Apr, Shift 2Q52The first and second ionization constants of a weak dibasic acid are and …
Idea: pH of Polyprotic Acids
HardSingle correct - 2 Apr, Shift 2Q56At 25°C, 20.0 mL of 0.2 M weak monoprotic acid HX is titrated against 0.2 M NaOH. The pH of the solution (a) at the start of the titration…
Idea: pH at Titration Half-Equivalence Point
MediumSingle correct - 4 Apr, Shift 1Q74The pH of a solution obtained by mixing mL of M solution with mL of M solution…
Idea: Basic Buffer pH Calculation
MediumNumerical value - 4 Apr, Shift 2Q5520 mL of a solution of acetic acid required 28.4 mL of 0.1 M NaOH for its neutralization. A solution (X) was prepared by mixing 20 mL of…
Idea: Acidic Buffer pH Calculation
EasySingle correct - 5 Apr, Shift 1Q56Arrange the following resultant mixtures in increasing order of their pH values A. 10 mL 0.2 M + 25 mL 0.1 M HCl B. 10…
Idea: pH of Strong Acid and Strong Base Mixtures
MediumOther - 6 Apr, Shift 2Q56Given is a concentrated solution of a weak electrolyte of concentration 'c' and dissociation constant 'K'. The degree of…
Idea: pH of Weak Acids and Bases
HardSingle correct
JEE Main 20253 questions in 3 shifts
- 4 Apr, Shift 2Q71x mg of (molar mass = 58) is required to be dissolved in 1.0 L of water to produce a pH of 10.0 at 298 K. The value of…
Idea: pH of Strong Acids and Bases
EasyNumerical value - 7 Apr, Shift 1Q54An aqueous solution of HCl with pH 1.0 is diluted by adding equal volume of water (ignoring dissociation of water). The pH of HCl solution…
Idea: pH of Strong Acids and Bases
EasySingle correct - 7 Apr, Shift 2Q72One litre buffer solution was prepared by adding 0.10 mol each of and in deionised water. The change in…
Idea: pH Change on Adding Strong Acid/Base to Buffer
New ideaMediumNumerical value
JEE Main 20245 questions in 4 shifts
- 8 Apr, Shift 2Q62Given below are two statements : Statement (I) : A Buffer solution is the mixture of a salt and an acid or a base mixed in any particular…
Idea: Buffer Capacity and Range
New ideaEasyTwo statements - 1 Feb, Shift 1Q80Given below are two statements : Statement (I) : Potassium hydrogen phthalate is a primary standard for standardisation of sodium…
Idea: Indicator Selection for Titrations
EasyTwo statements - 1 Feb, Shift 1Q83for is and for is . The pH of…
Idea: pH of Weak Acid-Weak Base Salts
EasyNumerical value - 27 Jan, Shift 1Q63Given below are two statements : Statement (I) : Aqueous solution of ammonium carbonate is basic. Statement (II) : Acidic/basic nature of…
Idea: pH of Weak Acid-Weak Base Salts
EasyTwo statements - 30 Jan, Shift 2Q83The pH of an aqueous solution containing 1M benzoic acid () and 1M sodium benzoate is 4.5. The volume of benzoic…
Idea: Volume Ratios for Buffer Preparation
New ideaMediumNumerical value
JEE Main 20234 questions in 4 shifts
- 8 Apr, Shift 1Q86The titration curve of weak acid vs. strong base with phenolphthalein as indictor) is shown below. The…
Idea: pH of Acid-Base Indicators
New ideaMediumNumerical value · figure - 12 Apr, Shift 1Q85An analyst wants to convert 1L HCl of pH =1 to a solution of HCl of pH 2. The volume of water needed to do this dilution is _________ mL.…
Idea: pH of Strong Acids and Bases
Asked the year beforeEasyNumerical value - 13 Apr, Shift 2Q8520 mL of 0.1 M NaOH is added to 50 mL of 0.1 M acetic acid solution. The pH of the resulting solution is ______ (Nearest…
Idea: Buffer Formation via Partial Neutralization
New ideaMediumNumerical value - 15 Apr, Shift 1Q64Which of the following statement(s) is/are correct? (A) The pH of M HCl solution is 8. (B) The conjugate base of…
Idea: pH of Extremely Dilute Strong Acids/Bases
New ideaMediumOther
JEE Main 202211 questions in 9 shifts
- 25 Jul, Shift 1Q64mL of M is mixed with mL of M HCl. The pH of the mixture is nearest to : (Given :…
Idea: pH of Salt Solutions
New ideaMediumSingle correct - 25 Jul, Shift 2Q80In base vs. acid titration, at the end point methyl orange is present as
Idea: Predicting Indicator Color
New ideaMediumSingle correct - 26 Jul, Shift 2Q63Class XII students were asked to prepare one litre of buffer solution of pH 8.26 by their Chemistry teacher. The amount of ammonium…
Idea: Basic Buffer pH Calculation
Asked the year beforeMediumSingle correct - 26 Jul, Shift 2Q80Given below are two statements: one is labelled as **Assertion A** and the other is labelled as **Reason R**. **Assertion…
Idea: Predicting Indicator Color
New ideaMediumAssertion–reason - 28 Jul, Shift 1Q85for butyric acid () is . The pH of 0.2 M solution of butyric acid is __________…
Idea: pH of Weak Acids and Bases
Asked the year beforeEasyNumerical value - 29 Jul, Shift 2Q64200 mL of 0.01 M HCl is mixed with 400 mL of 0.01M . The pH of the mixture is __. Given: log 2 = 0.30, log 3 = 0.48, log…
Idea: pH of Mixed Strong Acids
New ideaMediumSingle correct - 29 Jul, Shift 2Q80A compound ‘X’ is a weak acid and it exhibits colour change at pH close to the equivalence point during neutralization of NaOH with…
Idea: Acid-Base Indicator Transition Range
New ideaEasySingle correct - 30 Jul, Shift 2Q5450 mL of 0.1 M is titrated against 0.1 M NaOH solution. When 10 mL of NaOH is added, the pH of the solution becomes…
Idea: Acidic Buffer pH Calculation
Asked the year beforeMediumNumerical value - 26 Jun, Shift 1Q8350 mL of 0.1 M is being titrated against 0.1 M NaOH. When 25 mL of NaOH has been added, the pH of the solution will be…
Idea: pH at Titration Half-Equivalence Point
New ideaEasyNumerical value - 27 Jun, Shift 2Q86pH value of 0.001 M NaOH solution is ________.
Idea: pH of Strong Acids and Bases
Asked the year beforeEasyNumerical value - 28 Jun, Shift 2Q64A student needs to prepare a buffer solution of propanoic acid and its sodium salt with pH 4. The ratio of…
Idea: Acidic Buffer pH Calculation
Asked the year beforeMediumSingle correct
JEE Main 202111 questions in 10 shifts
- 3 Aug, Shift 1Q55If 1 M solution of acetic acid is diluted times so that pH of the solution is doubled. The value of of is ( =…
Idea: pH of Weak Acids and Bases
Asked the year beforeHardNumerical value - 3 Aug, Shift 2Q55The pH of the solution resulted when 150 mL of 0.1 M ammonia solution is titrated with 50 mL of 0.1M HCl [ = 4.7] is…
Idea: Buffer Formation via Partial Neutralization
Asked the year beforeMediumNumerical value - 4 Aug, Shift 2Q57g of are required to produce 200 of an aqueous solution of pH 10.0. The value of…
Idea: pH of Strong Acids and Bases
New ideaMediumNumerical value - 26 Aug, Shift 1Q50Given below are two statements : Statement I : In the titration between strong acid and weak base methyl orange is suitable as an…
Idea: Indicator Selection for Titrations
New ideaMediumTwo statements - 26 Aug, Shift 1Q55The concentration in a mixture of 5.0 mL of 0.0504 M and 2 mL of 0.0210 M solution is…
Idea: Basic Buffer pH Calculation
New ideaMediumNumerical value - 31 Aug, Shift 2Q56The pH of a solution obtained by mixing 50 mL of 1 M HCl and 30 mL of 1 M NaOH is . The value of is __________.…
Idea: pH of Strong Acids and Bases
New ideaEasyNumerical value - 26 Feb, Shift 2Q56The pH of ammonium phosphate solution, if of phosphoric acid and of ammonium hydroxide are 5.23 and 4.75 respectively, is…
Idea: pH of Weak Acid-Weak Base Salts
HardNumerical value - 25 Jul, Shift 2Q56Assuming that is completely ionised in aqueous solution under the given conditions the concentration of…
Idea: pH of Strong Acids and Bases
New ideaEasyNumerical value - 16 Mar, Shift 2Q56Sulphurous acid () has and . The pH of 0.588 M …
Idea: pH of Polyprotic Acids
New ideaMediumNumerical value - 17 Mar, Shift 1Q560.01 moles of a weak acid HA () is dissolved in 1.0 L of 0.1 M HCl solution. The degree of dissociation of HA is…
Idea: Common Ion Effect on Weak Acid pH
New ideaMediumNumerical value - 18 Mar, Shift 1Q55In order to prepare a buffer solution of pH 5.74, sodium acetate is added to acetic acid. If the concentration of acetic acid in the…
Idea: Acidic Buffer pH Calculation
New ideaEasyNumerical value
JEE Main 20204 questions in 4 shifts
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.