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What is the activity in Curie (\mathrm{Ci}) of 2 moles of an isotope of Plutonium for which mass number is 239 and half -life is 26000 yrs?

Option: 1

1.49\, \mathrm{Ci}


Option: 2

5.513 \times 10^{11} \mathrm{Ci}


Option: 3

14.9 \mathrm{Ci}


Option: 4

27.5 \mathrm{Ci}


Answers (1)

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\mathrm{\because-\frac{d N}{d t}=\lambda N \Rightarrow \frac{0.693}{t_{1 / 2}} \times n \times N_{A} }

\mathrm{-\frac{d N}{d t}=\frac{0.693 \times 2 \times 6.022 \times 10^{23}}{26000 \times 365 \times 60 \times 60 \times 24} }

\mathrm{\because 3.7 \times 10^{10} \mathrm{dps}=1 \text { Curie } }

\mathrm{\therefore-\frac{d N}{d t}=101.79 \times 10^{10} \mathrm{dps}=27.5 \text { Curie }}

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shivangi.bhatnagar

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