Starting with a sample of pure\[^{66}Cu,\] 7/8 of it decays into Zn in 15 min. The corresponding half-life is
AIEEE Solved Paper-2005
A)10 min
B) 15 min
C) 5 min
D) \[7\frac{1}{2}\] min
Correct Answer:
C
Solution :
The number of particles left undisintegrated, where,decay constant initial number of atoms andpresent number of atoms \[8={{e}^{\lambda \,t}}\] Taking log both sides, we get \[3\,\,\ln \,\,2=\lambda \,t\] Half life period