The mass number of Fe2+ is 56. How many neutrons are there in a single Fe2+ atom?

There are 30 neutrons in a single Fe2+ atom.

30

Explanation:

(i dont know if its correct i am in a rush,)

Number of neutrons = 56 – 26 = 30. Thus there are 30 neutrons in a single $F{{e}^{2+}}$ atom. Note: Neutron is generally a subatomic particle which is neutral in charge. Mass of the neutron is slightly greater than the mass of the proton.