In which of the following sets do all species have the same number of protons?

• A. H-1, H-2, He-4
• B. N-14, O-16, F-19
• C. Na-23, Mg-24, Al-27
• D. C-12, C-13, C-14

Answer: (D)

Verified step by step guidance

1. Recall that the number of protons in an atom is given by its atomic number, which defines the element itself.
2. Understand that isotopes of the same element have the same number of protons but differ in the number of neutrons, which affects their mass number.
3. Examine each set by identifying the elements and their atomic numbers (number of protons):
4. For example, in the set C-12, C-13, C-14, all are carbon isotopes, so they all have the same atomic number (6 protons) but different mass numbers.
5. Compare this with other sets where different elements are present, meaning different atomic numbers and thus different numbers of protons.