Those are called isotopes,
the answer is 3.
each element has its own unique number of protons (atomic number) but a different number of neutrons can be shown in example number 3.
Answer:
Noble gases.
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<span>The atoms of a chemical element can exist in different types. These are calledisotopes. They have the same number of protons (and electrons), but different numbers of neutrons.</span>
Mass is not created or destroyed
Answer:
this is the required answer look it once