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Friday, 9 October

JEE Main Physics · Nuclei

Radioactive Decay in JEE Main

Radioactive Decay (Physics, Nuclei) came 15 times in 11 of the 42 JEE Main shifts Lumi analysed, across 9 distinct ideas. 2 of them came in 2024–26; it was last asked in 2026.

Questions
15
in 11 shifts
Ideas asked
9
3 asked more than once
Numerical answer
2
13% of its questions
Pattern
Asked most years
rarely asked since 2024
Questions each year
0481’170’207’213’222’230’241’251’26

In the shifts Lumi analysed for each year.

Difficulty and format
Easy 7Medium 8Hard 0

Format

  • Single correct12 Q
  • Numerical value2 Q
  • Diagram based1 Q
Ideas inside the topic
9 ideas
Where it sits

Part of Nuclei, which had 38 questions in all. Radioactive Decay accounts for 39% of them. In Lumi's JEE taxonomy it belongs to Modern Physics.

Every question

All 15 Radioactive Decay questions

Newest first, each with its options and official answer.

  1. 8 Apr 2026, Shift 2 · Q44Two radioactive substances A and B of mass numbers 200 and 212 respectively, shows spontaneous α\alpha-decay with same QQ value of 1…MediumSingle correct
  2. 4 Apr 2025, Shift 2 · Q42A radioactive material P first decays into Q and then Q decays to non-radioactive material R. Which of the following figure represents…MediumDiagram basedHas a figure
  3. 8 Apr 2023, Shift 2 · Q44A radio active material is reduced to 1/8 of its original amount in 3 days. If 8×10−38\times10^{-3} kg of the material is left after 5 days…MediumSingle correct
  4. 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
  5. 28 Jul 2022, Shift 1 · Q48The half life period of a radioactive substance is 60 days. The time taken for 78\frac{7}{8}th of its original mass to disintegrate will…EasySingle correct
  6. 28 Jul 2022, Shift 1 · Q52A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The…EasyNumerical value
  7. 29 Jun 2022, Shift 1 · Q33The activity of a radioactive material is 2.56×10−32.56 \times 10^{-3} Ci. If the half life of the material is 5 days, after how many days the…EasySingle correct
  8. 3 Aug 2021, Shift 2 · Q18A radioactive isotope has a half life of T years. After how much time is its activity reduced to 6.25% of its original activity ?EasySingle correct
  9. 3 Aug 2021, Shift 2 · Q25A sample undergoing beta decay, reduced to 116th\frac{1}{16}^{\mathrm{th}} of its initial mass in 48 years. Its half life period is…EasyNumerical value
  10. 25 Jul 2021, Shift 1 · Q1The half-life of 198Au^{198}\mathrm{Au} is 3 days. If atomic weight of 198Au^{198}\mathrm{Au} is 198 g/mol then the activity of 2 mg of…MediumSingle correct
  11. 25 Jul 2021, Shift 1 · Q5Some nuclei of a radioactive material are undergoing radioactive decay. The time gap between the instances when a quarter of the nuclei…MediumSingle correct
  12. 16 Mar 2021, Shift 2 · Q10Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20 minutes.EasySingle correct
  13. 16 Mar 2021, Shift 2 · Q12The half-life of Au198\mathrm{Au^{198}} is 2.7 days. The activity of 1.50 mg of Au198\mathrm{Au^{198}} if its atomic weight is 198 g…MediumSingle correct
  14. 18 Mar 2021, Shift 1 · Q11A radioactive sample disintegrates via two independent decay processes having half lives T1/2(1)T_{1/2}^{(1)} and T1/2(2)T_{1/2}^{(2)} respectively.…MediumSingle correct
  15. 2 Apr 2017 (offline) · Q26A radioactive nucleus A with a half life T, decays into a nucleus B. At t=0t=0, there is no nucleus B. At sometime t, the ratio of the…MediumSingle correct