<u>Answer:</u>
The correct answer option is C. 4.18 g.
<u>Step-by-step explanation:</u>
We are given that Curium-243 has a half-life of 28.5 days. In a sample of 5.6 grams of curium-243 and we are to find how many grams will remain after 12 days.
To find the number of remaining grams, we will use the following formula:
where t is the time and h is the half life.
So substituting in the given values to get:
Therefore, 4.18 grams of curium-243 will remain after 12 days.