Question

4. DBearded waste of Co-60 must be stored until it is no longer radioactive. Cobalt-60

waste weighing 14.5g has been in storage før 26.5 years. How much of this radioisotope
was present when the sample was put in storage?

Answer 1

464 g radioisotope was present when the sample was put in storage

Further explanation

Given

Sample waste of Co-60 = 14.5 g

26.5 years in storage

Required

Initial sample

Solution

General formulas used in decay:

`\large{\boxed{\bold{N_t=N_0((1)/(2))^{t/t(1)/(2) }}}`

t = duration of decay

t 1/2 = half-life

N₀ = the number of initial radioactive atoms

Nt = the number of radioactive atoms left after decaying during T time

Half-life of Co-60 = 5.3 years

Input the value :

`\tt 14.5=No.(1)/(2)^(26.5/5.3)\\\\14.5=No.(1)/(2)^5\\\\No=\boxed{\bold{464~g}}`