JEE Main 2019PhysicsNuclear PhysicsMediumMCQ

JEE Main 2019Nuclear Physics Question with Solution

JEE Main 2019 (10 Apr Shift 1)

Question

Two radioactive materials A and B have decay constants 10λ and  λ , respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of A to that of B will be 1/e after a time:

Choose an option

Show full solutionCorrect option: B
Correct answer
B19λ

Step-by-step explanation

NA=N0e-10λt
NB=N0e-λt
NANB=1e=e-10λt+λt=e-9λt
1=9λt
t=19λ

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About this question

This is a previous-year question from JEE Main 2019, 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.