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Crystal Lattices: JEE Main previous year questions

Name: Crystal Lattices: JEE Main previous year questions
Creator: Lumi

24 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: 24; in 24 of 108 shifts
Years asked: 5/8; last asked 2023
Since 2024: Quiet; 0 questions in 2024–26
Weighted estimate: –; history: 0.2 a shift on average, typically 0.0–0.4

Key findings

01
Asked in 5 of 8 years with analysed shifts and in 24 of 108 shifts: 24 questions, #129 of 196 topics. The years that asked it were 1.5 apart on average. Last asked in 2023.
02
43% of its questions since 2020 tested an idea no earlier year had asked; 13 repeated an idea from the year before.
03
The most repeated idea is Unit Cell Density, asked 9 times in 9 shifts (2020, 2021, 2022, 2023), most often as “atoms per unit cell from density”.
04
JEE Main has asked 9 of the 49 ideas in this topic; 34 have never been asked, directly or inside another question.
05
Mostly asked as numerical value (67%); 67% need a numerical answer, 38% are easy and 0% hard. It went down from 0.4 to 0.0 questions a shift since 2024.
06
The skill tested most is calculation (58%), then multi-step (21%).

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: 3 in 12 shifts · 2021: 7 in 24 shifts · 2022: 7 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: 0.4; a shift, of 25
Since 2024: 0.0; -0.4
Usual gap: 1.5 yrs; between years asking it
Shifts with it: 24/108; 22% of analysed shifts

How it is asked

Difficulty, format and skill

Across all 24 questions on Crystal Lattices since 2017.

Difficulty

QUESTIONS

915

Easy9 · 38%
Medium15 · 63%
Hard0 · 0%

Format

Numerical value · 16 Q67%
Single correct · 8 Q33%

Skill tested

Calculation · 14 Q58%
Multi-step · 5 Q21%
Recall · 3 Q13%
Application · 2 Q8%

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.

’17’20’21’22’23’24’25’26

Idea asked for the first time
Idea asked in an earlier year

Coverage of the topic

JEE Main has asked 9 of the 49 ideas in this topic. 34 have never been asked yet.

9634

Asked directly9 · 18%
Touched inside another question6 · 12%
Never asked34 · 69%

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

Idea, year, question

Every idea JEE Main tested in this topic, with its eight years. Open one to read the questions.

ideaAskedShareYears’17’20’21’22’23’24’25’26

OpenRepeated9 · 38%38%4/8224
- 11 Apr ’23 S1 · Q82
  An atomic substance A of molar mass $12\ \mathrm{g\ mol^{-1}}$ has a cubic crystal structure with edge length of 300 pm. The no. of atoms…
  mediumNumerical valueAsked the year before
- 28 Jul ’22 S1 · Q82
  An element M crystallises in a body centred cubic unit cell with a cell edge of 300 pm. The density of the element is…
  mediumNumerical valueAsked the year before
- 28 Jul ’22 S2 · Q52
  Metal M crystallizes into a fcc lattice with the edge length of $4.0\times10^{-8}$ cm. The atomic mass of the metal is ______ g/mol.…
  easyNumerical valueAsked the year before
- 25 Jun ’22 S1 · Q82
  The distance between $\mathrm{Na^+}$ and $\mathrm{Cl^-}$ ions in solid NaCl of density $43.1\ \mathrm{g\ cm^{-3}}$ is __________…
  mediumNumerical valueAsked the year before
- 30 Jun ’22 S1 · Q61
  An element X has a body centred cubic (bcc) structure with a cell edge of 200 pm. The density of the element is 5 g cm $^{-3}$ . The number…
  mediumSingle correctAsked the year before
- 25 Feb ’21 S2 · Q52
  The unit cell of copper corresponds to a face centered cube of edge length 3.596 Å with one copper atom at each lattice point. The…
  mediumNumerical valueAsked the year before
- 22 Jul ’21 S2 · Q52
  A copper complex crystallising in a CCP lattice with a cell edge of 0.4518 nm has been revealed by employing X-ray diffraction studies.…
  mediumNumerical valueAsked the year before
- 3 Sep ’20 S1 · Q47
  An element with molar mass $2.7\times10^{-2}$ $\mathrm{kg\ mol^{-1}}$ forms a cubic unit cell with edge length 405 pm. If its density is…
  mediumNumerical valueNew idea
- 5 Sep ’20 S1 · Q40
  A diatomic molecule $\mathrm{X_2}$ has a body-centred cubic (bcc) structure with a cell edge of 300 pm. The density of the molecule is…
  mediumSingle correctNew idea
OpenRepeated4 · 17%17%2/83
OpenRepeated4 · 17%17%3/82
Open2 · 8%8%1/82
Open1 · 4%4%1/8
Open1 · 4%4%1/8
Open1 · 4%4%1/8
Open1 · 4%4%1/8
Open1 · 4%4%1/8

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

9 different ideas were tested; 4 came more than once.

Unit Cell Density9×
atoms per unit cell from density
Numerical value · 9 shifts · 7 numerical
Edge-Radius Relationships4×
atomic radius from unit cell edge
Numerical value · 4 shifts · 2 numerical
Empirical Formula from Void Occupancy4×
percentage of element from void occupancy
Numerical value · 4 shifts · 3 numerical
Tetrahedral and Octahedral2×
total voids in given mass of metal
Numerical value · 2 shifts · 2 numerical
14 Bravais Lattices Distribution1×
count crystal systems with a unit cell type
Numerical value · 1 shift · 1 numerical
Deriving Formula from Void Occupancy1×
formula from void occupancy in close packing
Single correct · 1 shift
BCC Neighbor Distances1×
coordination number of bcc
Numerical value · 1 shift · 1 numerical
Empirical Formula from Void Occupation1×
formula from void occupancy
Single correct · 1 shift
FCC Neighbor Distances1×
closest approach in fcc from edge length
Single correct · 1 shift

Idea	Times	Shifts	Format	Numerical
Unit Cell Densityatoms per unit cell from density	9	9	Numerical valueCalculation	7
Edge-Radius Relationshipsatomic radius from unit cell edge	4	4	Numerical valueCalculation	2
Empirical Formula from Void Occupancypercentage of element from void occupancy	4	4	Numerical valueCalculation	3
Tetrahedral and Octahedraltotal voids in given mass of metal	2	2	Numerical valueCalculation	2
14 Bravais Lattices Distributioncount crystal systems with a unit cell type	1	1	Numerical valueRecall	1
Deriving Formula from Void Occupancyformula from void occupancy in close packing	1	1	Single correctApplication	–
BCC Neighbor Distancescoordination number of bcc	1	1	Numerical valueRecall	1
Empirical Formula from Void Occupationformula from void occupancy	1	1	Single correctCalculation	–
FCC Neighbor Distancesclosest approach in fcc from edge length	1	1	Single correctCalculation	–

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

Crystal Lattices 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.

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.

Key findings

Questions a shift, year by year

Difficulty, format and skill

Difficulty

Format

Skill tested

New idea, or one asked before?

Coverage of the topic

Idea, year, question

Every idea inside this topic

Crystal Lattices questions, year by year

JEE Main 20236 questions in 6 shifts

JEE Main 20227 questions in 7 shifts

JEE Main 20217 questions in 7 shifts

JEE Main 20203 questions in 3 shifts

JEE Main 20171 question in 1 shift

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