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JAMB Physics 1983 Question 34

Question 34

Radioactivity and Nuclear Physics

Which of the following statements is CORRECT? I. The mass number is equal to the total number of protons and electrons in an atom II. The atomic number is equal to the number of protons in an atom III. The number of electrons in an atom is equal to the total number of protons and neutrons in the nucleus.

  1. A.I only
  2. B.II only
  3. C.III only
  4. D.I and II only
  5. E.II and III only.
Show the answer and explanation

Answer: B (II only)

Explanation

The atomic number is the number of protons. The mass number counts protons and neutrons (not electrons), and a neutral atom has as many electrons as protons.