JIPMER2004PhysicsNuclear Physics
The half life of a radioactive substance is 3.6 days. How much of 20 mg of this radioactive substance will remain after 36 days?
Options
- A0.0019 mg
- B1.019 mg
- C1.109 mg
- D0.019 mg
Correct answer
D. 0.019 mg
Step-by-step solution
Half life T_ 1 / 2 =3.6 days Initial quantity N₀=20 mg Total time =36 days The number of half lives n= t T_ 1 / 2 = 36 3.6 =10 Hence, mass of radioactive substance left after 10 half lives N=N₀ ( 1 2 )^n=20 1 1024 =0.019 mg