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Saturday, 31 October

JEE Main · Physics · Nuclei

Mean Life Calculation

JEE Main asked Mean Life Calculation 2 times in 2 of the 108 shifts Lumi analysed, in 2021 and 2023. It belongs to Radioactive Decay, in Nuclei (Physics). The longest wait between two years asking it was 2 years.

Updated 2026-10-24

Times asked
2
in 2 shifts
Years
2 of 8
First asked
2021
last in 2023
Pattern
Occasional
across the analysed shifts

Questions on this idea a shift, by year

2017–2026. Asked in 2021 and 2023. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift of 25 Physics questions.

00.050.10’170’200.03’210’220.07’230’240’250’26

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

Shift by shift

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

  • 20260 of 9
  • 20250 of 8
  • 20240 of 18
  • 20231 of 12
  • 20220 of 24
  • 20211 of 24
  • 20200 of 12
  • 20170 of 1

Asked in that shift More than once Not asked

How JEE Main framed it

Single correct is the usual form. Skill tested: application.

  • Relation of decay constants from half-life and mean life
  • Mean life from activity at two instants

Difficulty

Easy 2Medium 0Hard 0

Every question was multiple choice.

Every question

All 2 questions

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

  1. 11 Apr 2023, Shift 1 · Q33Two radioactive elements A and B initially have same number of atoms. The half life of A is same as the average life of B. If λA\lambda_A…EasySingle correct
  2. 26 Feb 2021, Shift 2 · Q1A radioactive sample is undergoing α\alpha decay. At any time t1t_1, its activity is A and another time t2t_2, the activity is…EasySingle correct

Shifts: 26 Feb 2021, Shift 2, 11 Apr 2023, Shift 1.

Same topic

Other ideas in Radioactive Decay

Radioactive Decay has 12 ideas JEE Main has asked; 9 of them came up in more than one question.

Topic analysisChapter analysisStudy this chapterAll repeated ideas