Here's how to determine the number of neutrons in an iron-56 atom:

* Atomic Number: Iron (Fe) has an atomic number of 26. This means every iron atom has 26 protons.

* Mass Number: The "56" in iron-56 represents the mass number, which is the total number of protons and neutrons in the nucleus.

* Calculation:

* Mass Number (56) - Atomic Number (26) = Number of Neutrons

* 56 - 26 = 30

Therefore, there are 30 neutrons in the nucleus of an iron-56 atom.