A Small Quantity Of Solution Containing  radionuclide (half-life 15 Hours) Of Activity 1.0 microcurie is Injected Into The Blood Of A Person. A Sample Of The Blood Of Volume 1 Cm3 taken After 5 Hours Show An Activity Of 296 Disintegrations Per Minute. Determine The Total Volume Of Blood In The Body Of The Person. .

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A small quantity of solution containing  radionuclide (half-life 15 hours) of activity 1.0 microcurie is injected into the blood of a person. A sample of the blood of volume 1 cm3 taken after 5 hours show an activity of 296 disintegrations per minute. Determine the total volume of blood in the body of the person.



Correct option is

If N0 be the initial mass (or no. of radionuclide) of a radioactive material, then the mass remaining after n half-lives is given by


The activity R is proportional to N, and so    


Here R0 = 1.0 microcurie = 10–6 curie





This is the activity in the blood after 5 hours. 

Now,  disintegrations/s are observed in 1 cm3 of blood. Therefore, the volume of the blood showing  is 






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