JEE Main202229 Jun 2022Morning ShiftPhysicsNuclear PhysicsActual
The activity of a radioactive material is 2 . 56 × 10 - 3 Ci . If the half life of the material is 5 days, after how many days the activity will become 2 × 10 - 5 Ci ?
Options
- A30 days
- B35 days
- C40 days
- D25 days
Correct answer
B. 35 days
Step-by-step solution
The activity of a radioactive sample at any time t is given by, A = A 0 2 - t T 1 2 ⇒ 2 × 10 - 5 = 2 . 56 × 10 - 3 × 2 - t 5 ⇒ 2 t 5 = 128 ⇒ t 5 = 7 ⇒ t = 35   days