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A and B are the two radioactive elements. The mixture of these elements show a total activity of 1200 disintegrations/minute. The half-life of A is 1 day and that of B is 2 days. What will be the total activity after 4 days ? Given, the initial number of atom in A and B are equal : |
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Answer» 200 dis/min Initial number of atoms is A and B are same `A_(0) alpha 1/T_(1//2)` `rArr A_(0)/A_(0) ((A))/((B)) =(48 hr)/(24 hr)=2` ALSO `A_(0) (A)+A_(0) (B)=1200` `rArr 3A_(0) (B)=1200` `A_(0) (B)=400` and `A_(0) (A)=800` So, `A(A)=(A_(0)(A))/(2^(4))=(800)/(16)=50` `and A(B)=(A_(0)(B))/((2)^(2))=(400)/(4)=100` Hence total activity after 4 days is `=A_(0) (A)+A_(0)(B)=50+100=150"dis/min"` |
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