SCIENCE
EARTH SCIENCE
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
12, 500 years
|
|
|
13, 000 years
|
|
|
14, 000 years
|
|
|
11, 460 years
|
Detailed explanation-1: -1. If you had a sample of 4, 000 radioactive atoms, how many atoms would remain after 5 half-lives? 125 radioactive atoms.
Detailed explanation-2: -The half-life of C-14 is 5, 730 years. If an excavated sample of plant or animal origin from an archaeological site had a measured activity of 7 disintegrations per minute (dpm), the age of the sample could be fixed at about 5, 730 years ± 40 years. At 3.5 dpm, the age would be about 11, 640 years and so on.
Detailed explanation-3: -This is done by multiplying the number of half-lives that have passed by the half-life decay constant of the parent atom (again, this value is determined in a laboratory).
Detailed explanation-4: -The half-life for radioactive decay of C−14 is 5730 years. An archaeological artifact containing wood had only 80% of the C−14 found in a living tree.