there is this thing called isotopes it means that atoms of the same element can have a different number of neutrons. if there is a change in the no. of neutrons, there will definitely be a change in the mass number.
so the answer is A) mass number
The quantity that can vary among atoms of the same element is the mass number, which represents the sum of the number of protons and neutrons in an atom. ;
Atoms of the same element can vary in their mass number, which is due to differing numbers of neutrons. This concept leads to the creation of isotopes, where the atomic number remains constant while the mass number changes. Therefore, the answer is A) mass number.
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