At time t = 0, a material is composed of two radioactive atoms A and, B, where NA(0) = 2NB(0). The decay constant of both kind of radioactive atoms is λ .  However, A disintegrates to B and B disintegrates to C. Which of the following figures represents the evolution of NB(t)/NB(0) with respect to time t?

[ N A ( 0 ) = N o . o f A a t o m s a t t = 0 N B ( 0 ) = N o . o f B a t o m s a t t = 0 ]

 

Option 1 - <p>(a)</p>
Option 2 - <p>(b)</p>
Option 3 - <p>(c)</p>
Option 4 - <p>(d)</p>
5 Views|Posted 7 months ago
Asked by Shiksha User
1 Answer
A
7 months ago
Correct Option - 1
Detailed Solution:

d N B d t = λ N A λ N B = 2 λ N B ( 0 ) . e λ t λ N B                

d N B d t + λ N B = 2 λ N B ( 0 ) e λ t              

Solving it, N B ( t ) = N B ( 0 ) ( 1 + 2 λ t ) e λ t  

NB (t) is maximum when,

d N B d t = 0 t = 1 2 λ              

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Physics Nuclei 2025

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