Answer :
Final answer:
Using the concept of half-life for Radon-222, the activity of radon in the container after two half-lives (just over 8 days) would be approximately a quarter of its original value. The approximate value would be slightly less than 21.8 pCi/L.
Explanation:
We will need to utilize the concept of half-life in the context of radioactive decay. In this case, Radon-222 has a half-life of 3.82 days, meaning that after every 3.82 days, approximately half of the radon atoms in a sample will have decayed into other elements. After one half-life (3.82 days), the activity in the container would have decayed to approximately half its initial value (43.5 pCi/L). Likewise, after two half-lives (7.64 days), it would be about a quarter of the initial value (21.75 pCi/L). As the time period in your question is just slightly more than two half-lives, the radon activity in the container after 8 days will be slightly less than 21.75 pCi/L. Therefore, the closest answer in your list would be option B (21.8). However, please note, the actual value might be slightly less depending on the exact calculation.
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