Final answer:
The correct special notation for an atom of oxygen with 8 protons and 9 neutrons is 178O, where the atomic number is represented as the subscript and the mass number as the superscript.
Step-by-step explanation:
The special notation for an atom of oxygen with 8 protons and 9 neutrons is represented by the atomic number (Z) and the mass number (A), where Z is the number of protons, and A is the sum of the number of protons and neutrons. For an oxygen atom with 8 protons (which is the atomic number of oxygen) and 9 neutrons, the mass number would be 8 (protons) + 9 (neutrons) = 17. The representation of this isotope of oxygen is typically written with the atomic number as a subscript and the mass number as a superscript to the left of the chemical symbol for oxygen (O). Therefore, the correct notation is O-17 or 178O. This indicates an isotope of oxygen that has a total of 17 nucleons (protons plus neutrons) and an atomic number of 8.