7. different isotopes of carbon have different numbers of a. protons b. electrons c. neutrons d. positrons e. ions

C. Neutrons

Explanation:

Elements principal differentiation is their number in protons, this means that an atom with a different number of protons is NOT an isotope is a completely different element, for example, hydrogen and helium have a proton of difference (1 for H, 2 for He).

Positrons, electrons, and ions just change the charge in an element, this doesn't affect its mass, therefore, they are no isotopes.

By definition, an isotope is a variant of a particular chemical element that differs in neutron number (meaning isotopes have different masses) but has the same number of protons and electrons. Isotopes are represented with a superscript number to the left of the element, for example, for hydrogen, deuterium indicates one neutron and one proton.

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