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?

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

Given

Sample waste of Co-60 = 14.5 g

26.5 years in storage

Required

Initial sample

Solution

General formulas used in decay:  

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 :

answer: c.

explanation:

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.