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You start with a 100g sample of 198 Au. If the half-life of 198 Au is 2.70 days, how much would be left after a total of 8.10 days goes by?

a) 12.5g
b) 25g
c) 37.5g
d) 50g

1 Answer

3 votes

Final answer:

To find out how much of the 198 Au sample would be left after 8.10 days, we can use the formula for radioactive decay. After calculating the number of half-lives that have passed, we can determine the amount remaining. In this case, the correct answer is 12.5g.

Step-by-step explanation:

To calculate how much of the 198 Au sample would be left after 8.10 days, we need to determine how many half-lives have passed and use the formula:

Final amount = Initial amount * (1/2)^(number of half-lives)

In this case, the half-life of 198 Au is 2.70 days. To find the number of half-lives that have passed in 8.10 days, we divide the total duration by the half-life:
Number of half-lives = 8.10 days / 2.70 days = 3 half-lives

Now we can calculate the final amount:
Final amount = 100g * (1/2)^(3) = 100g * (1/8) = 12.5g

Therefore, the correct answer is 12.5g.

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