Two or more nuclides are iso tones, if they have the same neutron number. Hence, (a) ‌8O16=8 protons +8 neutrons (b) ‌7N15=7 protons +8 neutrons (c) ‌6C14=6 protons +8 neutrons (d) ‌13Al27=13 protons +14 neutrons (e) ‌9F17=9 protons +8 neutrons