If 100 grams of Carbon-14 decay after 2 half lives, how much of the sample would remain?

After one half-life, 50 grams of Carbon-14 would remain from the original 100 grams. After the second half-life, half of the remaining 50 grams would decay, leaving 25 grams.

So, after 2 half-lives, 25 grams of Carbon-14 would remain.

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