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Activity of a ratio active sample is 64 x 10-4 dps and half life is 5 days. After how many days its activity becomes 5 x 10-5 dps.(1) 30 days(2) 25 days(3) 35 days(4) 40 days |
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Answer» Correct option is (3) 35 days \(A = \frac{A_0}{2^n}\) \(2^n = \frac{A_0}A =\frac{64\times10^{-4}}{5 \times 10^{-5}} = 128 = 2^7\) n = 7 7 half lifes 7 x 5 = 35 days |
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