Question

what is the number at the end of an isotopes name?
atomic number
neutron number
mass number
electron number

Explanation:

Isotopes are variants of an element with the same atomic number (protons) but different mass numbers (sum of protons and neutrons). The number at the end of an isotope's name (e.g., Carbon - 14) represents the mass number, as it accounts for the total number of nucleons (protons + neutrons). Atomic number is the number of protons (constant for an element), neutron number is mass number minus atomic number, and electron number varies with charge (not part of isotope naming).

Answer:

C. mass number