A small amount of solution containing a radioactive nucleide `A""^(x)` was administrated into the blood of a patient. The activity of the nucliede id `2xx10""^(3)`dps. Its half life is 15 hours. After 5 hours a sample of the blood drawn out from the patient. It,s activity was 16 dpm per mL.
At `A""^(x)`emits `alpha` ray. how many helium atoms present in hours?

Options

A. `1.558xx10""^(8)`atoms
B. `1.168xx10""^(8)`atoms
C. `7.79xx10""^(7)`atoms
D. `3.895xx10`atoms

Answer

b

Explanation

`(-dN)/(dt)=lamdaN,2xx10""^(3)=0.693/(15xx60xx60)N`
Initial no. of `A""^(x)` atom=`1.5584xx10""^(8)`atom. After 30 hours `A""^(x)` atom=`3.897xx10""^(8)` atom No. of He atom formed in 30 hours=`1.168xx10""^(8)`atom