Answer:
Their atoms have identical mass.
Explanation:
Oxygen-17 and Oxygen-18 are both isotopes of Oxygen.
Oxygen has three isotopes, Oxygen- 16, Oxygen-17 and Oxygen-18.
Oxygen- 16 has 8 protons and 8 neutrons and a mass number of 16.
Oxygen-17 has 8 protons and 9 neutrons and a mass number of 17.
Oxygen-18 has 8 protons and 10 protons and a mass number of 18.
The three isotopes therefore have the same atomic number ( the number of protons) but different mass numbers.
