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

danjs · Answer

That is 4 half lives. Divide the 300 in half 4 times.

triciaal · Answer

Do you understand what the half-life means?

triciaal · Answer

do you understand the previous response?

triciaal · Answer

@bsaranga  Welcome to Openstudy !!
the asker is not here. do you need help with this or are you just looking?

bsaranga · Answer

Hello @triciaal I'm new to OpenStudy. :) Let me try and answer this question.

triciaal · Answer

you don't have to if you don't want to. I realised you are new said   Welcome!!
I asked if you needed help or if you were just browsing

bsaranga · Answer

$$A=A_0(\frac{ 1 }{ 2 })^{\frac{ t }{ 5 }}$$
A_0 being the initial quantity, and t is the duration. Half life is basically exponential decay, so when the given data is substituted. We get the answer as 18.75g.

Final answer = C. 18.75g

bsaranga · Answer

@triciaal Thanks for the warm welcome.

triciaal · Answer

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