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`._(29)^(64)` Cu can decay by `beta^(-)` or `beta^(+)` emmision, or electron capture. It is known that `._(29)^(64)` Cu has a half life of `12.8` hrs with 40% probability of `beta^(-)` decay 20% probability of `beta^(+)` decay and 40% probability of electron capture. The mass of `._(29)^(64)` Cu is `63.92977amu whil e `._(30)^(64) Zn is 63.92914 amu` and `._(28)^(64) Ni is 63.92796 amu`. What is the half life for electron capture?A. `5.12` Hrs.B. 32 Hrs.C. `2.56` Hrs.D. 16 Hrs. |
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Answer» Correct Answer - B `._(29)^(64)Cu rightarrow._(30)^(64)Zn+_(-1)^(0)e+vec(V)Q=(m_(Zn)-m_(Cu))C^(2)` `._(29)^(64)Cu rightarrow ._(28)^(64)Ni+._(+1)^(0)e+VQ=(m_(Zn)-m_(Ni)-2me)C^(2)` ` ._(29)^(64)Cu+._(-0)^(0)e rightarrow ._(28)^(64)Ni+VQ=(m_(2n)-m_(Ni))C^(2)` `lambda=lambda_(1)+lambda_(2)+lambda_(3)(lambda_(1)=0.4lambda,lambda_(2)=0.2lambda,lambda_(3)=0.4lambda)` `T_(1//2) e-capture=(T_(1//2))/(0.4)=(12.8)/(0.4)=32` hrs. |
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