JEE Main 2019PhysicsNuclear PhysicsMediumMCQ

JEE Main 2019Nuclear Physics Question with Solution

JEE Main 2019 (12 Apr Shift 2)

Question

Half lives of two radioactive nuclei A and B are 10 minutes and 20 minutes, respectively. If, initially a sample has equal number of nuclei, then after 60 minutes, the ratio of decayed numbers of nuclei A and B will be:

Choose an option

Show full solutionCorrect option: D
Correct answer
D9:8

Step-by-step explanation

Half-life of A : t12(A)=10  minutes
Number of half-lives in 60 minutes are: 6010=6
  Number of decayed nuclei of A
NA=No-No26=6364No
Similarly, Half-life of B : t12(B)=20  minutes
Number of half-lives of B in 60 minutes are: 6020=3
Number of decayed nuclei of B
NB=No-No23=78No
  NA:NB=6364:78=9:8=9:8

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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.