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13.Nuclei
easy
If a radioactive material remains $25 \%$ after $16$ days, then its half life will be ......... days
A
$32$
B
$8$
C
$64$
D
$28$
Solution
(b)
$\frac{N}{N_0}=\left(\frac{N}{4 \times N}\right)$
$\frac{N}{N_0}=\left(\frac{1}{2}\right)^2$
$\text { or } n=2$
$2$ half lives in $16$ days
$\therefore \quad 1$ half life is in $8$ days
Standard 12
Physics
