You have a 10-gram sample of Carbon-14. Use the radio isotope decay graph to ans

ID: 275099 • Letter: Y

Question

You

have a 10-gram sample of Carbon-14. Use the radio isotope decay graph to answer the following questions.

Part 1
How much Carbon-14 is left (in grams) after 3 half lives?

Part 2
What is the percent of Nitrogen-14 present in the sample after 2 half-lives?

Part 3
If you detect the sample is 50% C-14 and 50% N-15, how old is it in years?

Part 4
How many grams of Carbon-14 is present after 4 half lives?

Part 5
Your sample contains 8.75 grams of Nitrogen-14. How old is it in years?

Decay of Carbon-14 10.0g 100 5.0g 50 2.50g ?) 1.25g 12.5 - 0 2 Number of half-lives (!half-life = 5730 years) 0 3 4

Part 1: After three half lives, 12.5 % (i.e. 1.25 grams) of C-14 will be present in the sample.

Part 2: After two half lives, 75% of C-14 has decayed to N-14 by beta decay. So sample will be 75 % N-14 after two half lives.

Part 3: 50% C-14 and 50% N-15 in sample means it has decayed for one half life time. So the sample is 5730 years old.

Part 4: After four half lives, all of the C-14 has decayed to N-14. So, sample will be 100% N-14 with no C-14 left.

Part 5: 8.75 grams of Nitrogen-14 will be present when C-14 has decayed for period of three half lives. So, sample is 5730 × 3 = 17190 years old.

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