Which of the following best describes the material that makes us the mantle?
1 answer:
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The rate at which radioactive substances disintegrate is a constant for a
given radioactive material.
- <u>The fossil is 710 million years old</u>.
Reasons:
The half-life of a radioactive material is the time it takes half of the nucleus
of a radioactive material to disintegrate into other forms of materials
through the given off of energy and particles.
The half life of Uranium 235 = 710 million years
The product of the decay of Uranium 235 = Lead 207
The mass of Uranium 235 in the fossil = 4 micrograms
The mass of Lead 207 in the sample = 4 micrograms
Therefore, the mass of Lead 207 in the fossil is equal to the mass of
Uranium 235, therefore, a minimum of half of the Uranium 235 has
decomposed, which gives;
The time of decomposition of the Uranium 235 = 1 Half life = 710 million years
The age of the fossil = The time in which the Uranium has been
decomposing = The time of decomposition = 1 half life of Uranium 235 = 710
million years
- <u>The age of the fossil = 710 million years</u>
Using the formula for half-life, we get;
The fossil contains initially only Uranium 235 with a minimum mass of 4 mg
+ 4 mg = 8 mg, which gives;
N₀ = 8 mg
N(t) = The current mass of Uranium 235 = 4 mg
= 710 million years
Therefore;
t = 710
- <u>The age of the fossil, </u><u><em>t</em></u><u> = 710 million years</u>
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