NTA Abhyas JEE Main2020PhysicsNuclear PhysicsPractice
80 kg of a radioactive material reduces to 10 kg in 1 h . The decay constant of the material is
Options
- A5.80 × 10 - 4 s - 1
- B1.16 × 10 - 3 s - 1
- C2.32 × 10 - 3 s - 1
- D4.64 × 10 - 3 s - 1
Correct answer
A. 5.80 × 10 - 4 s - 1
Step-by-step solution
Fraction of material that remains undecayed 10 80 = 1 2 1 h T 1 / 2 3 = 1 h T 1 / 2 or T 1 / 2     =   60 3   min   =   20   min   = 1200   s Now,   λ = 0.693 T 1 / 2 = 0.693 1200 =   5.8   ×   10 - 4   s - 1