Question

question 12 (5 points)
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isotopes have
a) a different number of electrons.
b) different numbers of both protons and neutrons in their nuclei.
c) a different number of neutrons in their nuclei.
d) a different number of protons in their nuclei.

Explanation:

To determine the correct answer, we recall the definition of isotopes. Isotopes are atoms of the same element, which means they have the same number of protons (atomic number). The difference between isotopes lies in the number of neutrons in their nuclei (which affects the mass number).

• Option A: The number of electrons can change due to ionization, but isotopes are defined by nuclear composition (protons and neutrons), not electrons. So A is incorrect.
• Option B: Isotopes of the same element have the same number of protons (since the element is defined by the number of protons). So they cannot have different numbers of protons. B is incorrect.
• Option C: Isotopes have the same number of protons (same element) but a different number of neutrons. This matches the definition.
• Option D: A different number of protons would mean a different element, not an isotope of the same element. So D is incorrect.

Answer:

C. a different number of neutrons in their nuclei.