All sodium atoms have 11 protons. The nuclei of some sodium atoms contain 12 neutrons and others contain 11. These different forms of sodium are called .

10 years is the answer

all eukaryotic cell have mitochondria : )

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.