Question

. A sample of 4 g of cobalt isotope is produced. If the half-life of is 30 years, what will be the mass of the cobalt remaining after 90 years?

Answer 1

Half Life = 90/30 = 3 Half lives

Half Life = 30 years

So,

4 g Cobalt after 30 years = 4/2

=> 2 g

2 g Cobalt after next 30 years = 2/2

=> 1 g

1 g Cobalt after next 30 years = 1/2

=> 0.5 g

So, After 90 years, 0.5g of cobalt isotope will be left.