Determine The Amount Of  required To Provide A Source Of -particles Of 5 millicurie strength. The Half-life Of Po Is 138 Days. The Avogadro’s Number is . 

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Determine the amount of  required to provide a source of -particles of 5 millicurie strength. The half-life of Po is 138 days. The Avogadro’s number is 


Correct option is

The required strength (rate of -emission) of the source is  



The decay constant is  




Let N be the number of atoms in the sample of strength  disintegration/s. Then  





By the definition of Avogadro’s number,  atoms of  has a mass of 210 g. 





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