If a radioactive substance starts at 100 grams and decays to 12.5 grams in 21.6 hours, what is the substance's half-life? a. 3 hours b. 7.2 hours c. 14.4 hours d. 21.6 hours

Hello,

Your brainliest answer would be:

10.2

But I don’t not see a choice like that

So let’s go with the closest

B.7.2 hours

Plz mark me brainliest!

Hope this helps!

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Photosynthesis. . .