JEE Main 2021PhysicsNuclear PhysicsEasyMCQ

JEE Main 2021Nuclear Physics Question with Solution

JEE Main 2021 (26 Feb Shift 2)

Question

A radioactive sample is undergoing α decay, At any time t1, its activity is A and another time t2, the activity is A5. What is the average life time for the sample ?

Choose an option

Show full solutionCorrect option: C
Correct answer
Ct2-t1ln5

Step-by-step explanation

Let initial activity be A0

A=A0e-λt      ...1

A5=A0e-λt2     ...2

1÷2

5=eλt2-t1

λ=ln5t2-t1=1τ

τ=t2-t1ln5

Practice this on the real CBT interface

Solve this JEE Main question (and the rest of the Nuclear Physics chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.

Solve interactively →

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.