Answer: The number of protons in 100 oxygen atoms is atomicNumber 4 and mass number i.e. total number of protons and neutrons is16. Then the number of neutrons in this oxygen atom is = 16-8-8.So if we remove two neutrons from '0, the atomic number remainsthe same, but the mass will be reduced by 2 to 14. Thenthe sum of the changed oxygen atoms will be 40.