The radioactive nucleus undergoes a series of decay according to the scheme (given below). If the mass number and atomic number of A are 180 and 72 respectively, then what are these number for A4.
Correct answer: A. 172 and 69
- A. 172 and 69
- B. 172 and 70
- C. 174 and 70
- D. 176 and 70
Explanation
To summarise, in alpha decay, the atomic number decreases by 2 and the mass number decreases by 4 due to the emission of an alpha particle. In beta-minus decay, the atomic number increases by 1 while the mass number remains the same due to the emission of an electron. In beta-plus decay, the atomic number decreases by 1 while the mass number stays constant due to the emission of a positron. In gamma decay, there are no changes in atomic number or mass number; it involves the emission of high-energy electromagnetic radiation, making option A correct.
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Atomic nuclei contain protons and neutrons, with nuclear size, mass defect and binding energy describing their stability. The work covers alpha, beta and gamma decay, decay equations, half-life and decay rate, along with radiation safety and medical applications such as imaging, radiotherapy and tracers.
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