Answer:
There are required 70.1 years for the activity of a sample of cesium-137 to fall to 20.0 percent of its original value
Explanation:
The radioactive decay follows always first-order kinetics where its general law is:
Ln[A] = -Kt + ln[A]₀
<em>Where [A] is actual concentration of the atom, k is rate constant, t is time and [A]₀ is initial concentration.</em>
We can find rate constant from half-life as follows:
<em>Rate constant:</em>
t(1/2) = ln 2 / K
As half-life of Cesium-137 is 30.2 years:
30.2 years = ln 2 / K
<em>K = 0.02295 years⁻¹</em>
Replacing this result and with the given data of the problem:
Ln[A] = -Kt + ln[A]₀
Ln[A] = -0.02295 years⁻¹* t + ln[A]₀
Ln ([A] / [A₀]) = -0.02295 years⁻¹* t
<em>As you want time when [A] is 20% of [A]₀, [A] / [A]₀ = 0.2:</em>
Ln (0.2) = -0.02295 years⁻¹* t
70.1 years = t
<h3>There are required 70.1 years for the activity of a sample of cesium-137 to fall to 20.0 percent of its original value</h3>
Answer:
Explanation:
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There are four fundamental forces existing in the universe so called universal forces. They are the strong nuclear force, the weak nuclear force, the electromagnetic force and the gravitational force. The strong nuclear force is the strongest force acting while gravityis weakest.
Mass witch would be c i covered this in class
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