Final answer:
The atomic symbol for a mercury isotope with 122 neutrons is written as 20280Hg, with a mass number of 202.
Step-by-step explanation:
The question asks us to write the atomic symbol for a mercury (Hg) isotope with 122 neutrons. Mercury has an atomic number of 80, which means it has 80 protons. The mass number of an isotope is the sum of its protons and neutrons.
Thus, for a mercury atom with 122 neutrons, the mass number would be 80 (protons) + 122 (neutrons) = 202. The atomic symbol for this isotope of mercury would then be written as 20280Hg.