Princeton Review 16th Edition PT1 Q58

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58) For half-life questions, we need to know the original mass and the time it takes for 1 half-life. This problem tells us that the sample starts at 2 grams and has a half-life of 1.5 hours. We can set up an exponential equation to find out the remaining sample at any given time. Here is a generic equation to help solve half-life problems.

Where m(t) is mass at a given time, m(0) is the initial mass, t is time, and c is the half-life time

We know that m(0) is 2 grams, c is 1.5 hours, and t is 6 hours. Now, let's plug in our given values.

Answer: A