Question

what precentage of the initial radioactivity of cobalt-60 would be left after being stored for 32 years?

Answer 1

what precentage of the initial radioactivity of cobalt-60 would be left after being stored for 32 years?

After one half-life, 50%, or one-half of a radioactive element will be left.

half-life of the radioactive isotope of cobalt = 5.2714 years

so 32 years is almost exactly six six half lives .

Therefore the activity after six half lives is 1/64 of the original level,

1--------1/2

1/2--------1/4

1/4--------1/8

1/8--------1/16

1/16--------1/32

1/32--------1/64=0.015625

Answer = 1.56 percent