Final answer:
The question is asking about an atom with a mass number of 120 and 40 more neutrons than protons, but without the number of protons given, it is not possible to determine the number of neutrons.
Step-by-step explanation:
The subject of this question is Chemistry. The question is asking about an atom with a mass number of 120 which has 40 more neutrons than protons.
To find the number of neutrons, subtract the number of protons (which is equal to the atomic number) from the mass number. In this case, the number of protons is not given, so we do not have enough information to determine the number of neutrons.
It is important to note that the mass number is the sum of the protons and neutrons in an atom.