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Saturday, 31 October

JEE Main · Chemistry · Some Basic Concepts of Chemistry

Empirical Formula from Mass Percentage

JEE Main asked Empirical Formula from Mass Percentage 6 times in 6 of the 108 shifts Lumi analysed, in 2020, 2022 and 2026. It belongs to Mole Concept, in Some Basic Concepts of Chemistry (Chemistry). The longest wait between two years asking it was 4 years. In 2022 and 2026 it came in more than one shift of the same year.

Updated 2026-10-24

Times asked
6
in 6 shifts
Years
3 of 8
First asked
2020
last in 2026
Pattern
Frequent
across the analysed shifts

Questions on this idea a shift, by year

2017–2026. Asked in 2020, 2022 and 2026. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift of 25 Chemistry questions.

00.150.30’170.08’200’210.10’220’230’240’250.22’26

Raw count: 2017: 0 in 1 shift · 2020: 1 in 12 shifts · 2021: 0 in 24 shifts · 2022: 3 in 24 shifts · 2023: 0 in 12 shifts · 2024: 0 in 18 shifts · 2025: 0 in 8 shifts · 2026: 2 in 9 shifts.

Shift by shift

Each square is one analysed shift, in date order. Open a filled one for that paper.

  • 20262 of 9
  • 20250 of 8
  • 20240 of 18
  • 20230 of 12
  • 20223 of 24
  • 20210 of 24
  • 20201 of 12
  • 20170 of 1

Asked in that shift More than once Not asked

How JEE Main framed it

Numerical value is the usual form. Skill tested: calculation.

  • Empirical formula from analysis data
  • Empirical formula from mass percentage

Difficulty

Easy 2Medium 3Hard 1

3 of the 6 questions had a numerical answer.

Every question

All 6 questions

From the official JEE Main shift papers, newest first. Open one for the full question, the options and the official answer.

  1. 6 Apr 2026, Shift 1 · Q51An oxide of iron contains 69.9% iron, its empirical formula, is: (Given : Molar mass of Fe and O are 56 and 16 g mol−1^{-1} respectively.)EasySingle correct
  2. 4 Apr 2026, Shift 1 · Q732.02.0 g of a bromo hydrocarbon (X) was subjected to Carius analysis, gave 3.363.36 g of AgBr. The percentage of carbon in the compound (X)…MediumNumerical value
  3. 28 Jun 2022, Shift 2 · Q61Compound A contains 8.7% Hydrogen, 74% Carbon and 17.3% Nitrogen. The molecular formula of the compound is, Given : Atomic masses of C, H…MediumSingle correct
  4. 27 Jun 2022, Shift 2 · Q81116 g of a substance upon dissociation reaction, yields 7.5 g of hydrogen, 60 g of oxygen and 48.5 g of carbon. Given that the atomic…MediumNumerical value
  5. 24 Jun 2022, Shift 2 · Q61120 g of an organic compound that contains only carbon and hydrogen gives 330 g of CO2_2 and 270 g of water on complete combustion. The…EasySingle correct
  6. 2 Sep 2020, Shift 2 · Q50The ratio of the mass percentages of ‘C & H’ and ‘C & O’ of a saturated acyclic organic compound ‘X’ are 4 : 1 and 3 : 4 respectively.…HardNumerical value

Shifts: 2 Sep 2020, Shift 2, 24 Jun 2022, Shift 2, 27 Jun 2022, Shift 2, 28 Jun 2022, Shift 2, 4 Apr 2026, Shift 1, 6 Apr 2026, Shift 1.

Same topic

Other ideas in Mole Concept

Mole Concept has 18 ideas JEE Main has asked; 12 of them came up in more than one question. The 12 most asked are below.

Topic analysisChapter analysisStudy this chapterAll repeated ideas