Question

question 11
atoms of the same element can have different atomic masses because,
they cant have different masses
the number of electrons can vary
the number of protons can vary
the number of neutrons can vary

Explanation:

Atoms of the same element have the same number of protons (defining the element). Electrons contribute little to mass. Neutrons, along with protons, make up atomic mass. Different neutron numbers (isotopes) lead to different atomic masses.

Answer:

the number of neutrons can vary