When a radioactive element emits a β-particle, the mass number of the atom will be:
Correct answer: D. Remain the same
- A. Increased by 1
- B. Decreased by 1
- C. Increased by 2
- D. Remain the same
Explanation
When a radioactive element emits a beta particle, the mass number of the atom will remain the same. A beta particle is an electron, and it has no mass. The only thing that changes when a beta particle is emitted is the atomic number of the atom. The atomic number is the number of protons in the nucleus, and it is what determines the chemical element of the atom. When a beta particle is emitted, a neutron in the nucleus decays into a proton, an electron, and an antineutrino. The proton remains in the nucleus, but the electron is emitted. This increases the atomic number of the atom by one, but the mass number remains the same.
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