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NDA 2019 GAT · General Knowledge · Nuclear and Modern Physics · hard

When a nucleus emits a beta particle, its

Single correct option

When a nucleus emits a beta particle, its
  1. A. atomic number decreases by two and mass number by four
  2. B. atomic number increases by one and mass number remains the same
  3. C. atomic number remains the same and mass number increases by one
  4. D. mass number decreases by one and atomic number is unchanged
Show answer and solution

Answer: (B) atomic number increases by one and mass number remains the same

In beta-minus decay a neutron changes into a proton and an electron, which is emitted. The proton count rises by one, while the total number of nucleons stays constant. The first option describes alpha decay, not beta decay.
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Original question written in the NDA 2019 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake