An atom of C-12 in the ground state and an atom of C-13 in the ground state are defined as isotopes of carbon because these atoms have the same number of protons and

Regents Chemistry Exam January 2025 Question 4.

4. An atom of C-12 in the ground state and an atom of C-13 in the ground state are defined as isotopes of carbon because these atoms have the same number of protons and

   
   

(1) the same number of neutrons

(2) the same number of electron shells

(3) a different number of neutrons

(4) a different number of electron shells

Solution:

Isotopes have the same number of protons but a different number of neutrons. Choice 3 is the correct answer.

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