Answer:
a) number of neutrons
Explanation:
A sodium ion is formed when an electron is removed from a sodium atom. This means that the atom's number of electrons changes, but the number of neutrons remains unchanged.
However, as the number of electrons changes, the electric charge and the electronic structure change, which means that a sodium atom and a sodium ion do not have the same number of electrons, nor do they have the same electric charge or electronic structure.
Therefore, option a) is the correct option.
