Starting with a sample of pure {}^{66}Cu,frac{7}{8} of it decays into Zn in 15, minutes

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13.Nuclei

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Starting with a sample of pure ${}^{66}Cu,\frac{7}{8}$ of it decays into $Zn$ in $15\, minutes$. The corresponding half life is..........$minutes$

A

$15$

B

$10$

C

$7\frac{1}{2}$

D

$5$

(AIIMS-2008)

Solution

$\frac{7}{8}$ days of Cu decays.

$\therefore $ Cu undecayed, $\mathrm{N}=1-\frac{7}{8}=\frac{1}{8}=\left(\frac{1}{2}\right)^{3}$

$\therefore $ No. of half lifes $=3$

$\mathrm{n}=\frac{\mathrm{t}}{\mathrm{T}}$ or $3=\frac{15}{\mathrm{T}}$

$\Rightarrow$ half life period, $\mathrm{T}=\frac{15}{3}=5$ $minutes$

Standard 12

Physics

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