Answer:
A neutral atom of Carbon-12 contains six protons, six neutrons, and six electrons; therefore, it has a mass number of 12 (six protons plus six neutrons).
Carbon-13 (13C) is a natural, stable isotope of carbon with a nucleus containing six protons and seven neutrons and six electrons.
Neutral carbon-14 contains six protons, eight neutrons, and six electrons; its mass number is 14 (six protons plus eight neutrons).
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