NTA Abhyas JEE Main2020PhysicsNuclear PhysicsPractice
Find the decay constant (in s − 1 ) of Co 55 radionuclide if its activity is known to decrease 4 % per hour. The decay product is non-radioactive.
Options
- A1 . 1   ×   10 - 5   s - 1
- B1 . 10   ×   10 - 2   s - 1
- C1 . 1   ×   10 2   s - 1
- D1 . 09   ×   10 - 5   s - 1
Correct answer
A. 1 . 1   ×   10 - 5   s - 1
Step-by-step solution
The initial activity of nuclei   A 0   =   λ N 0 Activity of nuclei at time t, A   =   λ N =   λ N 0 e – λ t   A   =   A 0 e – λ t   ...(1) Since activity decreases at 4 . 0 % per hour, so the activity of Co 55 radionuclide at t   =   1   hr , A   =   A 0   –   η A 0   =   A 0 ( 1   –   η ) , where η   =   0 . 04     ...(2) Takin