JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 27 August 2021, Shift 1, Physics Q19

Question 19 of 90 in this shift, Physics question 19 of 30, Section A.

There are

10^{10}

radioactive nuclei in a given radioactive element. Its half-life time is 1 minute. How many nuclei will remain after 30 seconds ? (

\sqrt{2}=1.414

)

(1) $10^5$
(2) $2\times10^{10}$
(3) $7\times10^{9}$ Official answer
(4) $4\times10^{10}$

Official answer

Option 3

NTA final key.

Chapter: Nuclei
Topic: Radioactive Decay
Idea tested: Half-Life Calculations

Same idea in other shifts

Asked 10× in all

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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.