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13.Nuclei
medium
A radioactive material has a half-life of $8$ years. The activity of the material will decrease to about $1/8$ of its original value in .......... $years$
A
$256$
B
$128$
C
$64$
D
$24$
Solution
(d) $\frac{A}{{{A_0}}} = {\left( {\frac{1}{2}} \right)^{t/{T_{1/2}}}}$
==> $\frac{1}{8} = {\left( {\frac{1}{2}} \right)^{t/8}}$
==> $t = 24\,years.$
Standard 12
Physics
