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Saturday, 31 October

JEE Main 2022 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 26 June 2022, Shift 2, Physics Q48

Question 48 of 90 in this shift, Physics question 18 of 30, Section A.

A radioactive nucleus can decay by two different processes. Half-life for the first process is 3.0 hours while it is 4.5 hours for the second process. The effective half-life of the nucleus will be :
  1. (1)3.75 hours
  2. (2)0.56 hours
  3. (3)0.26 hours
  4. (4)1.80 hoursOfficial answer

Official answer

Option 4

NTA final key.

Chapter
Nuclei
Topic
Radioactive Decay
Idea tested
Parallel Decay Branching

Same idea in other shifts

Asked 2× in all
  1. 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

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.