本题目来源于试卷: Nuclear & Quantum Physics E.3 Radioactive Decay，类别为 IB物理学
[单选题]
A 1.20 kg sample of a ra+vh-7 : umw3:kgm aakco 2jxk6r4 pm tckf9;,vdioactive isotope decaying via beta decay with a half-life of 30 minutes is observed in a closed container in a laboratory. The decay results in a daughter nucleucmv;f9,4k trps that is also a solid. What is the approximate total mass measured after 90 minutes?
A. 0.00 kg
B. 0.15 kg
C. 0.60 kg
D. 1.20 kg
参考答案: D
本题详细解析:
Explanation: For each half-life, half of the remaining nuclides in the sample decay to a different nuclide. In this situation, three half lives occur in the 90 minutes, so only one eighth of the original isotope remains. Because the daughter nuclides are also solid, however, they remain in the sample. The decay products of beta decay include the daughter nuclide, the beta particle (an electron), and an anti-neutrino. The mass of the electron and the anti-neutrino are negligible compared to the parent nuclide. Because the daughter nuclides contain the same number of nucleons as the parent nuclides, there is effectively no change in mass of the sample.
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