Question

3 which part of the atom is responsible for the different mass numbers in isotopes? a electron cloud b protons only c entire atom d nucleus

Explanation:

Isotopes are atoms of the same element with different mass numbers. The mass number is determined by the sum of protons and neutrons, which are located in the nucleus. So the part of the atom responsible for different mass - numbers in isotopes is the nucleus.

Answer:

D. Nucleus