Respuesta :
Answer:
Therefore the Uranium-235 must be stored safely for a time of 7075.71 million years.
Explanation:
Half life of Uranium-235 is given as 710 million years.
Uranium-235 is considered safe only when its radioactive level has dropped to 0.1 % of the original level.
The formula for half life of any element is
N = [tex]N_0[/tex] [tex](\frac{1}{2}) ^{\frac{t}{t_{half \hspace{0.1cm} life}} }[/tex] .... where N is the final amount after depletion
⇒ [tex]0.001N_0[/tex] = [tex]N_0 (\frac{1}{2} )^{\frac{t}{710 \times 10^{6} }[/tex] .... where it is given that N = 0.001 [tex]N_0[/tex] is the
amount that will be considered safe with
respect to radioactivity.
⇒ t = [tex]710 \times 10^6 \times \frac{(\log{0.001})}{(\log{0.5})}[/tex] = 7075.71 million years.
Therefore the Uranium-235 must be stored safely for a time of 7075.71 million years.
Thus we can say that U-235 must be stored securely for a very, very long time after which it can be considered safe.
