How do you determine the number of neutrons in an atom?

The correct method to determine the number of neutrons in an atom is to subtract the atomic number from the mass number. The atomic number represents the number of protons in the nucleus of an atom, which is also equal to the number of electrons in a neutral atom. The mass number is the total count of protons and neutrons in the nucleus. Therefore, to find the number of neutrons, you take the mass number (which accounts for both protons and neutrons) and subtract the atomic number (which only accounts for protons).

For instance, if an element has a mass number of 12 and an atomic number of 6, the number of neutrons would be calculated as follows: 12 (mass number) - 6 (atomic number) = 6 neutrons. This calculation is foundational in understanding atomic structure and isotopes, where variations in neutron numbers lead to different isotopes of the same element. Other options do not provide the correct framework for calculating neutrons, either misrepresenting the relationships between protons, neutrons, and electrons, or focusing on irrelevant counts.