In what respect does an atom of magnesium differ from a magnesium ion (mg^{2+})?
a. the ion has a more stable electronic arrangement than the atom.
b. the positive charge on the nucleus of the ion is two units greater than the nuclear charge on the atom.
c. the ion has two more protons than the atom.
d. the ion will react more readily with free cl₂. (e)the ion has two more planetary electrons than the atom. can anyone explain this one?

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.