Cobalt-60 has a half-life of about 5 years.

How many grams of a 300 g sample will remain after 20 years?

A. 0.0625 g

B. 9.375 g

C. 18.75 g

D. 37.5 g

Question

Cobalt-60 has a half-life of about 5 years.

How many grams of a 300 g sample will remain after 20 years?

A. 0.0625 g

B. 9.375 g

C. 18.75 g

D. 37.5 g

yuii · Answer

I think it's C.

sooobored · Answer

do you know the definition of a half life?

sooobored · Answer

oh wait, no need to go through that, you are correct

sooobored · Answer

20 years is the equivalent of going through 4 half-lives

4 half lives is the equivalent of dividing by 2 4 times or dividing by 16

300/16=18.75

yuii · Answer

Thank you.