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1 mg redium has 2.68xx10^18 atoms. Its half life is 1620 years. How many radium atoms will disintegrate from 1 mg of pure radium in 3240 years ? |
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Answer» `2.01xx10^9` As `N/N_0=m/m_0=(1/2)^n` Mass of radium left after 2 half lives is `m=m_0(1/2)^n = 1XX(1/2)^2 =1/4` = 0.25 MG Mass of radium DISINTEGRATED =1-0.25 =0.75 mg Number of radium atoms disintegrated = 0.75x 2.68 x `10^18=2.01xx10^18` |
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