The following nuclei do not lie in the band of stability. How would they be expe
ID: 528542 • Letter: T
Question
The following nuclei do not lie in the band of stability. How would they be expected to decay? And what the expected daughter nuclide is? (a)^28 _15 P (b)^235_92 U (c)^37_3 Li (e)^245_96 Cm Define the term half-life and illustrate it with an example. Archeologists have dated a civilization to 15, 600 yrs ago. If a living sample gives 20.0 counts per minute per gram C, what would be the number of counts per minute per gram C for a rice grain found at the site? (C -14 half-life is 5730 years) Write the balanced nuclear equation for the production of the following transuranium elements (elements with atomic numbers greater than 92): (a) bcrkcliuni-244, made by the reaction of Am-241 and He-4 (b) fcrmium-254, made by the reaction of Pu-239 with a large number of neutrons (c) lawrcncium-257, made by the reaction of Cf-250 and B-11 (d) dubnium-260. made by the reaction of Cf-249 and N - 15Explanation / Answer
4.
A = Aoe(- t) ----------------(1)
= 0.693/t1/2 = 0.693/5730 = 1.20x10-4 year-1
Taking ln on both the sides
ln A = ln Ao - t
A = ?
Ao = 20 cpm
ln Ao = ln 20 - (1.20x10-4 year-1) x (15600 year)
ln Ao = 2.99 -1.88
ln Ao = 1.11
Ao = 3.03 cpm
So the counts in the rice sample is 3.03 cpm
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