Question

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Answer 1

Answer:

d and e - Sodium and antimony

Explanation:

The atomic numbers remain the same, while the mass numbers change (because neutrons are being added or taken away).

sodium has an atomic number of 19 and a mass number of 39 - in d, it has an atomic number of 19 but a mass number of 40. therefore, it is an isotope

antimony has an atomic number of 51 and a mass number of 121.60 - in e, it has an atomic number of 51, but a mass number of 123. therefore, it is an isotope