Q. 11. Carbon−14 has a half-life of 5730 years. After 17,190 years, only 3g remains. What was the mass of the original sample?
Determine Initial Mass: We need to determine the initial mass of a Carbon-14 sample that has decayed to 3g after 17,190 years. The half-life of Carbon-14 is 5730 years. We can use the formula for exponential decay to find the original mass.
Calculate Number of Half-Lives: First, let's determine how many half-lives have passed in 17,190 years. We do this by dividing the total time by the half-life of Carbon−14.Number of half-lives = Total time / Half-life = 17,190 years / 5730 years
Calculate Remaining Mass: Calculating the number of half-lives:Number of half-lives = 5,73017,190=3This means that the Carbon−14 sample has gone through 3 half-lives.
Calculate Initial Mass: Now, we can use the fact that after each half-life, the mass of the radioactive substance is halved. After 3 half-lives, the mass would be halved 3 times.Initial mass = Remaining mass ×(2Number of half-lives)
Final Calculation: Calculating the initial mass:Initial mass = 3g×(23)=3g×8
Final Calculation: Calculating the initial mass:Initial mass = 3g×(23)=3g×8Final calculation of the initial mass:Initial mass = 3g×8=24gThe original mass of the Carbon−14 sample was 24 grams.
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