A few days ago
Nohbdy

Chemistry help with half-lives?

The mass of cobalt-60 in a sample is found to have decreased from .800g to .200g in a period of 10.5 years. From this information, calculate the half-life of cobalt-60.

Top 2 Answers
A few days ago
Howard H

Favorite Answer

It has gone to 1/4 of the original. After one half-life it would be down to 1/2 and after two half-lives it would be down to 1/4. So 10.5 years is two half-lives and one half-life is 5.25 years, or 63 months.
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A few days ago
ignoramus
IT took 10.5 years to go to 1/4 of its original value.

That is 2 half lives.

So one half life is 5.25 years.

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