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A sample originally contained 1.28 g of a radioisotope. It now contains 1.12 g of its daughter isotope. How many half-lives have passed since the sample originally formed? 3 4 8 16
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Mar 9, 2017
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A sample originally contained 1.28 g of a radioisotope. It now contains 1.12 g of its daughter isotope.
How many half-lives have passed since the sample originally formed?
3
4
8
16
Chemistry
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Murali Suriar
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3
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Answer:
3
Step-by-step explanation:
Stackyyflow
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Mar 12, 2017
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Stackyyflow
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3
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The answer is 3.
The relation between number of half-lives (n) and decimal amount remaining (x) can be expressed as:
We need to calculate n, but we need x to do that. To calculate what p
ercentage of a radioactive species would be found as daughter material, we must calculate what amount remained:
1.28 -
1.12 = 0.16
If 1.28 is 100%, how much percent is 0.16:
1.28 : 100% = 0.16 : x
x = 12.5%
Presented as decimal amount:
x = 0.125
Now, let's implement this in the equation:
Because of the exponent, we will log both sides of the equation:
Therefore, 3 half-lives have passed
since the sample originally formed.
Ahmad Ragab
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Mar 13, 2017
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Ahmad Ragab
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