JEE Main 2021PhysicsNuclear PhysicsMediumMCQ

JEE Main 2021 — Nuclear Physics Question with Solution

JEE Main 2021 (27 Aug Shift 1)

Question

There are 1010 radioactive nuclei in a given radioactive element. Its half-life time is 1 min. How many nuclei will remain after 30 s?(2=1.414)

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Show full solutionCorrect option: A
Correct answer
A7×109

Step-by-step explanation

Recall the relationship between the present amount of element and the initial amount of element in terms of the decay constant, N=N0e-λt, now the relation between decay constant and half-life, t12=0.693λ, ⇒N=N0e-0.693tt12

⇒N=1010e-0.35=7×109.

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About this question

This is a previous-year question from JEE Main 2021, covering the Nuclear Physics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.