The Half-life Of A Radioactive Substance Is  against . Calculate The Decay Rate For  atoms Of The Substance.

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The half-life of a radioactive substance is  against . Calculate the decay rate for  atoms of the substance.


Correct option is

According to Rutherford and Soddy law, the rate of radioactive decay at any time t is given by 


where  is decay constant and N is the number of atoms left at time t. If Tbe the half-life, then  




Substituting this value of  atoms in eq. (i), we get 





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The half-life of  against . Calculate the activity of 1 g sample of . Avogadro’s number is .