. 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?

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.

answer: b.

explanation:

energy can be converted from one form to another, but it cannot be created or destroyed in ordinary chemical or physical means. do not understand what you are asking but hope this