Cobalt-60 has a half-life of 5.25 years. How much of the substance would remain after two half-lives?

Hey there!

A half-life means after a certain amount of time, half of that substance will be gone/changed after that time.

So, it gets divided in half 2 times.

1 ÷ 2 = 1/2

1/2 ÷ 2 = 1/4

One fourth of the substance would remain after two half-lives.

Hope this helps!

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