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WAEC Chemistry 2020 Objective — Question 45

Question 45 of 50 from the West African Examinations Council (WAEC) Chemistry 2020 Objective paper, with the correct answer and a full explanation.

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The atomic number of an atom would be equal to its mass number if it A. has a totally filled valence shell. B. has a high charge to mass ratio. C. does not contain neutrons. D. exhibits isotopy.

  • A. has a totally filled valence shell
  • B. has a high charge to mass ratio
  • C. does not contain neutronsCorrect
  • D. exhibits isotopy

Explanation

Mass number = Proton number + Neutron number. If neutron number=0, then Mass number = Atomic number + 0 = Atomic number. Thus, the atomic number would equal the mass number if the atom does not contain neutrons.

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