A radio-isotope has a half- life of 5 years. fraction of atoms of this material that would decay in

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13.Nuclei

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A radio-isotope has a half- life of $5$ years. The fraction of the atoms of this material that would decay in $15$ years will be

A

$1/8$

B

$2/3$

C

$7/8$

D

$5/8$

Solution

(c) $\frac{N}{{{N_0}}} = {\left( {\frac{1}{2}} \right)^{15/5}} = \frac{1}{8}$

==> Decayed fraction $ = 1 – \frac{1}{8} = \frac{7}{8}$

Standard 12

Physics

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