Question
Question: A nucleus of \(Ux_{1}\) has a half life of \(24.1\) days how long a sample of \(Ux_{1}\)will take to...
A nucleus of Ux1 has a half life of 24.1 days how long a sample of Ux1will take to change to 90% of Ux1
A
80 days
B
40 days
C
20 days
D
10 days
Answer
80 days
Explanation
Solution
: Here, λ=T1/20.693=24.10.693=0.02876day−1
N=N0−90%ofN0=10N0
As N=N0e−λt
∴10N0=N0e−λtor101=e−λtor1=eλt
Or loge10=λt
∴t=λ1loge10=0.028702.303log10=0.028762.303×1=80days