COMEDK2016PhysicsNuclear Physics
15 / 16 th of a radioactive sample disintegrates in 2 ~h . Mean life of radioactive sample is approximately
Options
- A30 ~min
- B43 ~min
- C21 ~min
- D1.5 ~min
Correct answer
B. 43 ~min
Step-by-step solution
The undecayed nuclei in a radioactive sample are given by Given, N=N₀- 15 16 N₀= 1 16 N₀, t=2 ~h N₀ 16 =N₀ ( 1 2 )^ 2 t_ 1 / 2 ( 1 2 )^ 2 t_ 1 / 2 = 1 16 = ( 1 2 )⁴ 2 t_ t / 2 =4 t_ 1 / 2 = 1 2 ~h =30 ~min Mean life, =1.44 t_ 1 / 2 =1.44 30=43.2 ~min 43 ~min