An alpha particle is emitted from 88Ra226. What is the mass and atomic number of the daughter nucleus ?
Correct answer: C. 222 - 86
- A. 224 - 84
- B. 220 - 80
- C. 222 - 86
- D. 226 - 87
Explanation
An alpha particle contains 2 protons and 2 neutrons, so alpha emission reduces the mass number by 4 and the atomic number by 2: A = 226 - 4 = 222 and Z = 88 - 2 = 86. The daughter is therefore radon-222, written with mass number 222 and atomic number 86. The likely trap is option a, which subtracts 2 from both numbers instead of subtracting 4 from the mass number.
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About Radioactive Decay
Radioactive decay is the spontaneous transformation of unstable nuclei, described by decay constant, activity, half life and the exponential decay law. Work includes alpha, beta and gamma emissions, decay equations and remaining nuclei, with half life distinguished from the time required for complete decay.
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