Question

All isotopes of a given element must have the same

Answer 1

Isotopes of any given element all contain the same number of protons, so they have the same atomic number (for example, the atomic number of helium is always 2). Isotopes of a given element contain different numbers of neutrons, therefore, different isotopes have different mass numbers.

Answer 2

number of protons

Step-by-step explanation:

Isotopes of any given element all contain the same number of protons, so they have the same atomic number

e.g: the atomic number of helium is always 2.

Isotopes of a given element contain different numbers of neutrons, therefore, different isotopes have different mass numbers.