Manipal MET2011PhysicsNuclear Physics
The half-life of the isotope ₁₁ Na ²⁴ is 15 h . How much time does it take for 7 8 th of a sample of this isotope to decay?
Options
- A75 h
- B65 h
- C55 h
- D45 h
Correct answer
D. 45 h
Step-by-step solution
Let initial amount be N₀ . Remaining amount N=N₀- 7 N₀ 8 = N₀ 8 N=N₀ ( 1 2 )^n array ll & N₀ 8 =N₀ ( 1 2 )^n & ( 1 2 )^3= ( 1 2 )^n & n=3 array t T_ 1 / 2 =3 gathered t 15 =3 or t=15 3 t=45 ~h gathered