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Friday, 9 October

JEE Main 2022 · PhysicsNumerical answerNumerical valueEasyCalculation

JEE Main 28 July 2022, Shift 1, Physics Q52

Question 52 of 90 in this shift, Physics question 22 of 30, Section B.

A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be __________ hours.

Official answer

15

NTA final key (2022 Session 2).

Chapter
Nuclei
Topic
Radioactive Decay
Idea tested
Integer Half-Life Shortcuts

Same idea in other shifts

Asked 2× in all
  1. 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

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 42 of the 174 JEE Main shifts held from 2017 to 2026.