Nuclear Physics And Radioactivity Question 330
Question: The activity of a radioactive sample is measured as 9750 counts per minute at t = 0 and as 975 counts per minute at t = 5 minutes. The decay constant is approximately [CBSE PMT 1997]
Options:
A) 0.230 per minute
B) 0.461 per minute
C) 0.691 per minute
D) 0.922 per minute
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Answer:
Correct Answer: B
Solution:
$ A=A_{0}{{e}^{-\lambda t}}\Rightarrow 975=9750\ {{e}^{-\lambda \times 5}} $
$ \Rightarrow {{e}^{5\lambda }}=10 $
$ \Rightarrow 5\lambda ={\log_{e}}10=2.3026{\log_{10}}10=2.3026 $
$ \Rightarrow \lambda =0.461 $
BETA
