What percentage of original radioactive atoms is left after five half lives.......... %

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13.Nuclei

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What percentage of original radioactive atoms is left after five half lives..........$\%$

A

$0.3$

B

$1$

C

$31$

D

$3.125$

Solution

(d) Fraction of atoms remains after five half lives

$\frac{N}{{{N_0}}} = {\left( {\frac{1}{2}} \right)^{t/T}} = {\left( {\frac{1}{2}} \right)^{5T/T}} = \frac{1}{{32}}$

==> Percentage atom remains $ = \frac{1}{{32}} \times 100 = 3.125\% $

Standard 12

Physics

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