NEET-XII-Physics
13: Nuclei
- #9Obtain the amount of
necessary to provide a radioactive source of 8.0 mCi strength. The half-life of is 5.3 years.
Ans : The strength of the radioactive source is given as:
Where,
N = Required number of atoms
Half-life of, .gif)
= 5.3 years
= 5.3 × 365 × 24 × 60 × 60
= 1.67 × 108 s
For decay constant λ, we have the rate of decay as:
Where, λ
For
:
Mass of 6.023 × 1023 (Avogadro’s number) atoms = 60 g
∴Mass of
atoms 
Hence, the amount of necessary for the purpose is 7.106 × 10-6 g.