NEETAtomic StructureHard
Question
The activity of radioactive sample is measured as 9750 counts per minute at t = 0 and as 975 counts per minute at t = 5 minutes, and decay constant is approximately :
Options
A.0.922per minute
B.0.270 per minute
C.0.461 per minute
D.0.39per minute
Solution
We know that
= λN
Now,
= λN0; 
= λNt
9750 = λN0; 975 = λNt
⇒ N0 = 10t
We now that
Nt = N0e-λt
= e-λt ⇒ 
= e-λ.5
Taking log on both sides,
- 1 = - 5λ ×
λ =
× 2.303 = 0.461 per minute.
= λNNow,
= λN0; = λNt9750 = λN0; 975 = λNt
⇒ N0 = 10t We now that
Nt = N0e-λt
= e-λt ⇒ = e-λ.5Taking log on both sides,
- 1 = - 5λ ×
λ =
× 2.303 = 0.461 per minute.Create a free account to view solution
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