Iron has atomic number 26. It exists as the isotopes $^{54}\text{Fe}$, $^{56}\text{Fe}$, $^{57}\text{Fe}$ and $^{58}\text{Fe}$. Which statement gives the reason that these isotopes have the same chemical properties?
- AThey have similar mass numbers.
- BThey have the same number of electrons in their outer shells.
- CThey have the same number of neutrons in their nuclei.
- DThey have the same number of protons in their nuclei.