Answer:
Explanation:
Initial radioactivity = 20 GBq
half life of source Mo = 2.7 days
dN / dt = N₀ λ where dN / dt is initial activity , N₀ is initial number of atoms and λ is disintegration constant .
λ = .693 / half life
= .693 / 2.7
= .257
dN / dt = N₀ λ
20k = N₀ x .257
N₀ = 20 k /.257
[tex]N = N_0e^{-\lambda t }[/tex]
= 20 k /.257 x [tex]e^{-.257\times 7 }[/tex]
= 20k x .64383
dN / dt = N λ
dN / dt = 20k x .64383 x .257
= 3.3 GBq.
