If Bismuth-212 has a half-life of 60.5 seconds, how many grams of the sample will be left after 121 seconds?

Depends on how many grams of the sample exist.

Think of half life as the amount of time it takes to split the item in half. With that half life, divide starting the grams by 2 (for the first 60.5 seconds). Because the question is asking for 121 seconds, divide the grams you just divided by 2 again. That should get you your answer.

Hope this helps!

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