Multiple choice general knowledge science & technology

The atomic number of an atom is:

  1. the number of electrons

  2. the number of protons

  3. the number of neutrons

  4. the number of protons plus the number of neutrons
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B Correct answer
Explanation

The atomic number is defined as the number of protons in the nucleus of an atom. This number uniquely identifies an element. It is not the number of electrons (which can vary in ions), neutrons (which vary in isotopes), or the sum of protons and neutrons (which is the mass number).

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